Bodyweight facts and evidence

Read the key facts about obesity and cancer risk, and find the supporting evidence from academic research and scientific studies to see why we say what we do.

Cancer Research UK and Weight Concern teamed up to develop a programme to help people keep a healthy weight. The tips are based on research and scientific evidence [1].

One study looked at the effect of giving the Ten Top Tips leaflet to people trying to lose weight [1]. Eight weeks later, people who had used the leaflet had lost an average of 2 kg, compared to 0.4 kg in those who didn’t receive the leaflet. After eight months, people using the leaflet had lost an average of 3.8 kg, and also reported an improvement in quality of life.

A small study of people using the Ten Top Tips leaflet also found that initially, it was an effort to remember to use some of the tips, but that over time it got easier to remember to follow the tips, until they became automatic [2].

In general, it takes different people different amounts of time to develop habits like those suggested in the Ten Top Tips [3].

Evidence shows that making small, simple changes can develop into healthy habits that have a long-term impact on behaviour and health [4].

References

1. Lally, P., Chipperfield, A. & Wardle, J. Healthy habits: efficacy of simple advice on weight control based on a habit-formation model. International journal of obesity 32, 700–7 (2008). View summary on PubMed

2. Lally, P., Wardle, J. & Gardner, B. Experiences of habit formation: a qualitative study. Psychology, health & medicine 16, 484–9 (2011). View summary on PubMed

3. Lally, P., van Jaarsveld, C. H. M., Potts, H. W. W. & Wardle, J. How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology 40, 998–1009 (2010). View resource

4. Lally, P. & Gardner, B. Promoting habit formation. Health Psychology Review 7, S137–S158 (2013). View resource

Major studies confirm that being overweight or obese increases the risk of various cancers [5-8]. The World Health Organisation (WHO) says that overweight and obesity are the most important known avoidable causes of cancer after tobacco [9].

Researchers estimate that overweight and obesity are behind around 17,000 cases of cancer each year in the UK [10]. This number may well increase in the future since the number of people who are overweight is increasing.

The latest statistics for England show that the proportion of adults with a healthy BMI decreased, and around a quarter of adults are obese, and the figures are similar in the other UK nations [11-14].

References

5. Bianchini, F., Kaaks, R. & Vainio, H. Overweight, obesity, and cancer risk. The Lancet Oncology 3, 565–574 (2002). View summary on PubMed

6. International Agency for Research on Cancer (IARC). Weight Control and Physical Activity. IARC Handbooks of Cancer Prevention/ World Health Organization, International Agency for Research on Cancer 6, 1–315 (2002). View resource

7. Renehan, A. G., Tyson, M., Egger, M., Heller, R. F. & Zwahlen, M. Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies. The Lancet 371, 569–78 (2008). View summary on PubMed

8. Reeves, G. K. et al. Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ 335, 1134 (2007). View summary on PubMed

9. World Health Organization. Report of a Joint WHO / FAO Expert Consultation on Diet, Nutrition and the Prevention of Chronic Diseases. 160 (2003). View resource

10. Parkin, D. M. & Boyd, L. 8. Cancers attributable to overweight and obesity in the UK in 2010. British journal of cancer 105 Suppl, S34–7 (2011). View summary on PubMed

11. Health and Social Care Information Centre. Statistics on Obesity , Physical Activity and Diet: England 2014. 102 (2014). View resource

12. Scottish Government Statistician Group. OBESITY INDICATORS 2013 Monitoring Progress for the Prevention of Obesity Route Map. 38 (2013). View resource

13. Statistical Publication Unit. Welsh Health Survey 2012. 163 (2012). View resource

14. Department of Health, S. S. and P. S. HEALTH SURVEY NORTHERN IRELAND 2010 / 11: Obesity Analysis. (2010). View resource

Scientists have estimated that anywhere between 7% and 15% of breast cancer cases in developed countries are caused by obesity [10, 15-18]. Over a hundred studies show that women who are overweight or obese and have been through the menopause have higher breast cancer risks [7, 19, 20].

Two large studies funded by Cancer Research UK - the EPIC study and the Million Women Study - have found that obese women have a 30% higher risk of postmenopausal breast cancer than women with a healthy weight [8, 20].

Obesity does not increase the risk of breast cancer in women before their menopause [7, 8, 20]. Putting on weight over time can also increase the risk of breast cancer. Studies have found that:

• Putting on 2-10 kg (4.4-22 lb) after the age of 50 increases the risk of breast cancer by 30% [21].
• Putting on 25 kg (55 lb) after the age of 18 increases the risk of breast cancer by 45% [16].

References

7. Renehan, A. G., Tyson, M., Egger, M., Heller, R. F. & Zwahlen, M. Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies. The Lancet 371, 569–78 (2008). View summary on PubMed

8. Reeves, G. K. et al. Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ 335, 1134 (2007). View summary on PubMed

16. Eliassen, H. A., Colditz, G. A., Rosner, B., Willett, W. C. & Hankinson, S. E. Adult weight change and risk of postmenopausal breast cancer. JAMA : the journal of the American Medical Association 296, 193–201 (2006). View summary on PubMed

19. Renehan, A. G., Soerjomataram, I. & Leitzmann, M. F. Interpreting the epidemiological evidence linking obesity and cancer: A framework for population-attributable risk estimations in Europe. European journal of cancer (Oxford, England : 1990) 46, 2581–92 (2010). View summary on PubMed

20. Lahmann, P. H. et al. Body size and breast cancer risk: findings from the European Prospective Investigation into Cancer And Nutrition (EPIC). International journal of cancer. Journal international du cancer 111, 762–71 (2004). View summary on PubMed

21. Ahn, J. et al. Adiposity, adult weight change, and postmenopausal breast cancer risk. Archives of internal medicine 167, 2091–102 (2007). View summary on PubMed

Obesity is one of the most important causes of bowel cancer [6, 9, 10]. Some groups have estimated that being overweight or obese causes about 11-14% of bowel cancer cases [10, 15, 17, 18].

Many large studies have found that bowel cancer is more common in overweight or obese people [7, 22-25]. Two of the largest studies so far, including the EPIC study, have found that obese men have about 50% higher risks of bowel cancer than those with a healthy weight [23, 24].

When BMI is used to measure body fat, studies tend to find that only obese men have a higher risk of bowel cancer. But when researchers use waist circumferences or waist-to-hip ratios, both obese men and women have higher risks of bowel cancer [24]. This suggests that, for women at least, fat around the stomach is more of a problem than fat elsewhere on the body [26].

References

6. International Agency for Research on Cancer (IARC). Weight Control and Physical Activity. IARC Handbooks of Cancer Prevention/ World Health Organization, International Agency for Research on Cancer 6, 1–315 (2002).View resources

7. Renehan, A. G., Tyson, M., Egger, M., Heller, R. F. & Zwahlen, M. Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies. The Lancet 371, 569–78 (2008). View summary on PubMed

9. World Health Organization. Report of a Joint WHO / FAO Expert Consultation on Diet, Nutrition and the Prevention of Chronic Diseases. 160 (2003). View resources

10. Parkin, D. M. & Boyd, L. 8. Cancers attributable to overweight and obesity in the UK in 2010. British journal of cancer 105 Suppl, S34–7 (2011). View summary on PubMed

15. Danaei, G. et al. Causes of cancer in the world: comparative risk assessment of nine behavioural and environmental risk factors. The Lancet 366, 1784–93 (2005). View summary on PubMed

17. Boyle, P. et al. European Code Against Cancer and scientific justification: third version (2003). Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 14, 973–1005 (2003). View summary on PubMed

18. Renehan, A. G. et al. Incident cancer burden attributable to excess body mass index in 30 European countries. International journal of cancer. Journal international du cancer 126, 692–702 (2010). View summary on PubMed

22. Larsson, S. C. & Wolk, A. Obesity and colon and rectal cancer risk: a meta-analysis of prospective studies. The American journal of clinical nutrition 86, 556–65 (2007). View summary on PubMed

23. Adams, K. F. et al. Body mass and colorectal cancer risk in the NIH-AARP cohort. American journal of epidemiology 166, 36–45 (2007). View summary on PubMed

24. Pischon, T. et al. Body size and risk of colon and rectal cancer in the European Prospective Investigation Into Cancer and Nutrition (EPIC). Journal of the National Cancer Institute 98, 920–31 (2006). View summary on PubMed

25. Ma, Y. et al. Obesity and risk of colorectal cancer: a systematic review of prospective studies. PloS one 8, e53916 (2013). View summary on PubMed

26. Dai, Z., Xu, Y.-C. & Niu, L. Obesity and colorectal cancer risk: a meta-analysis of cohort studies. World journal of gastroenterology : WJG 13, 4199–206 (2007). View summary on PubMed

A large body weight is one of the most important causes of womb cancer. A 2011 study estimated that more than a third of womb cancers in the UK are caused by being overweight or obese [10].

Studies have consistently found that obese people are two to three times more likely to develop womb cancer than people with a healthy bodyweight [8, 19, 27].

References

8. Reeves, G. K. et al. Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ 335, 1134 (2007). View summary on PubMed

10. Parkin, D. M. & Boyd, L. 8. Cancers attributable to overweight and obesity in the UK in 2010. British journal of cancer 105 Suppl, S34–7 (2011). View summary on PubMed

19. Renehan, A. G., Soerjomataram, I. & Leitzmann, M. F. Interpreting the epidemiological evidence linking obesity and cancer: A framework for population-attributable risk estimations in Europe. European journal of cancer (Oxford, England : 1990) 46, 2581–92 (2010). View summary on PubMed

27. Bjørge, T., Engeland, A., Tretli, S. & Weiderpass, E. Body size in relation to cancer of the uterine corpus in 1 million Norwegian women. International journal of cancer. Journal international du cancer 120, 378–83 (2006). View summary on PubMed

Being overweight or obese increases the risk of a type of oesophageal cancer (cancer of the foodpipe) called “oesophageal adenocarcinoma” [10].

Overweight people are over 80% more likely to develop this cancer than people of a healthy weight, and the risk in obese people is even more [28].

Experts have estimated that in the UK it causes about 1 in 5 cases of this type of cancer [10]. In fact, the rates of oesophageal adenocarcinoma in the UK are among the highest in the world, especially in men [29]. Some studies have suggested that, in Western countries, this type of cancer may be becoming more common because of rising levels of obesity [28, 30, 31].

References

10. Parkin, D. M. & Boyd, L. 8. Cancers attributable to overweight and obesity in the UK in 2010. British journal of cancer 105 Suppl, S34–7 (2011). View summary on PubMed

28. Turati, F., Tramacere, I., La Vecchia, C. & Negri, E. A meta-analysis of body mass index and esophageal and gastric cardia adenocarcinoma. Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 24, 609–17 (2013). View summary on PubMed

29. The Cancer Research UK Statistical Information Team. European Age-Standardised rates. GLOBOCAN 2008 v1.2, IARC, version 1.2 (2011). View resources

30. Kubo, A. & Corley, D. A. Body mass index and adenocarcinomas of the esophagus or gastric cardia: a systematic review and meta-analysis. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 15, 872–8 (2006). View summary on PubMed

31. Merry, A. H. H., Schouten, L. J., Goldbohm, R. A. & van den Brandt, P. a. Body mass index, height and risk of adenocarcinoma of the oesophagus and gastric cardia: a prospective cohort study. Gut 56, 1503–11 (2007). View summary on PubMed

 

The gastric cardia is the part of the stomach that is connected to the oesophagus. Cancer of this part of the stomach has become more common in developed countries, and scientists think that this is closely linked to obesity [28, 30]. This cancer can sometimes be referred to as cancer of the oesophagogastric junction or gastroesophageal junction [32, 33].

As with oesophageal cancer, more than 1 in 5 cases of this cancer may be caused overweight or obesity, and the risk is higher for those who also smoke [32]. The risk of gastric cardia cancer is nearly doubled in obese people compared to those of a healthy weight [28, 30].

Higher BMI and fat around the belly are both linked to a 10-14% increased risk of pancreatic cancer in men and women [8, 34, 35]. We don’t have clear evidence about exactly why this is, but it may be linked to some of the changes in hormone levels that are caused by obesity [35].

The risk increases with higher BMI, and it is estimated that around one out of ten pancreatic cancers may be caused by being overweight or obese [10, 18]. Those who are overweight when they are younger and gain more weight as they get older are at around 50% higher risk than those who keep a healthy weight from the age of 18 [36].

References

8. Reeves, G. K. et al. Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ 335, 1134 (2007). View summary on PubMed

10. Parkin, D. M. & Boyd, L. 8. Cancers attributable to overweight and obesity in the UK in 2010. British journal of cancer 105 Suppl, S34–7 (2011). View summary on PubMed

34. Aune, D. et al. Body mass index, abdominal fatness and pancreatic cancer risk: a systematic review and non-linear dose-response meta-analysis of prospective studies. Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 23, 843–52 (2012). View summary on PubMed

35. World Cancer Research Fund/ American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. 537 (AICR, 2007). View resource

36. Genkinger, J. M. et al. A pooled analysis of 14 cohort studies of anthropometric factors and pancreatic cancer risk. International journal of cancer. Journal international du cancer 129, 1708–17 (2011). View summary on PubMed

Studies have estimated that having a high body weight accounts for nearly a quarter of kidney cancers [10, 18]. And many studies have consistently shown that higher BMI is linked to an increased risk of kidney cancer [8, 35, 37]. The most recent study into the size of the risk showed that higher BMI increases the risk of kidney cancer by 31% [35].

References

8. Reeves, G. K. et al. Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ 335, 1134 (2007). View summary on PubMed

10. Parkin, D. M. & Boyd, L. 8. Cancers attributable to overweight and obesity in the UK in 2010. British journal of cancer 105 Suppl, S34–7 (2011). View summary on PubMed 

18. Renehan, A. G. et al. Incident cancer burden attributable to excess body mass index in 30 European countries. International journal of cancer. Journal international du cancer 126, 692–702 (2010). View summary on PubMed

35. World Cancer Research Fund/ American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. 537 (AICR, 2007). View resource

37. Bergström, A. et al. Obesity and renal cell cancer--a quantitative review. British journal of cancer 85, 984–90 (2001). View summary on PubMed

The WCRF report that obesity is a convincing cause of liver cancer [78, 79]. This large meta-analysis of all the literature, published in 2015, showed that being either overweight or obese increases the risk of liver cancer. This analysis confirms what many other studies have shown in the last few years, including one study looking at 5.2 million people in the UK [42, 43, 80].

References

42. Larsson, S. C. & Wolk, A. Overweight, obesity and risk of liver cancer: a meta-analysis of cohort studies. British journal of cancer 97, 1005–8 (2007). View summary on PubMed

43. Chen, Y., Wang, X., Wang, J., Yan, Z. & Luo, J. Excess body weight and the risk of primary liver cancer: an updated meta-analysis of prospective studies. European journal of cancer (Oxford, England : 1990) 48, 2137–45 (2012). Vew summary on PubMed

78. World Cancer Research Fund & American Institute for Cancer Research. Continuous Update Project Report: Diet , nutrition , physical activity and liver cancer. (2015). View resource

79. Bos, M., Renkema, M., Stam, B. & Wageningen, N.-E. V. Systematic Literature Review Report. (2006).

80. Bhaskaran, K., Douglas, I., Forbes, H., Leon, D. A. & Smeeth, L. Body-mass index and risk of 22 specific cancers : a population-based cohort study of 5.24 million UK adults. Lancet 6736, 1–11 (2014). View summary on PubMed

Obesity is known to cause formation of gallstones, which can increase the risk of cancer of the gallbladder [35, 38]. And the hormonal changes that result from having more body fat could also increase the risk of gallbladder cancer.

It is estimated that nearly a fifth of gallbladder cancers may result from people being overweight or obese [10, 18]. Compared to men, more than double the number of cases in women seem to be linked to excess body weight [38].

References

10. Parkin, D. M. & Boyd, L. 8. Cancers attributable to overweight and obesity in the UK in 2010. British journal of cancer 105 Suppl, S34–7 (2011). View summary on PubMed

18. Renehan, A. G. et al. Incident cancer burden attributable to excess body mass index in 30 European countries. International journal of cancer. Journal international du cancer 126, 692–702 (2010). View summary on PubMed

35. World Cancer Research Fund/ American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. 537 (AICR, 2007). View resource

38. Larsson, S. C. & Wolk, A. Obesity and the risk of gallbladder cancer: a meta-analysis. British journal of cancer 96, 1457–61 (2007). View summary on PubMed

 

The World Cancer Research Fund concluded that obesity is probably linked to an increased risk of aggressive prostate cancer, based on a 2014 meta-analysis of all the evidence [77]. Obesity isn't linked with risk of prostate cancer overall. So it is unclear whether this means obesity is causing people to develop aggressive prostate cancers, or whether in people who are obese, it is harder to diagnose prostate cancers at an early stage, so people are more likely to be diagnosed with aggressive or advanced prostate cancers [77]. We will need more research to show which of these explanations could be right.

References

77. World Cancer Research Fund International. Continuous Update Project Report: Diet, Nutrition Physical Activity, and Prostate Cancer. 2014. View resource

There is some evidence that being overweight or obese could increase the risk of many other types of cancer, including:

  • Brain cancer [39, 40]
  • Leukaemia [8, 41]
  • Multiple myeloma [44, 45]
  • Non-Hodgkin lymphoma [8, 46, 47]
  • Ovarian cancer, before the menopause [8, 48, 49]
  • Thyroid cancer [18, 51]

But the evidence for a link with these other cancer types is not strong enough to know for sure if there is a link.

References

8. Reeves, G. K. et al. Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ 335, 1134 (2007). View summary on PubMed

18. Renehan, A. G. et al. Incident cancer burden attributable to excess body mass index in 30 European countries. International journal of cancer. Journal international du cancer 126, 692–702 (2010). View summary on PubMed

39. Benson, V. S., Pirie, K., Green, J., Casabonne, D. & Beral, V. Lifestyle factors and primary glioma and meningioma tumours in the Million Women Study cohort. British journal of cancer 99, 185–90 (2008). View summary on PubMed

40. Shao, C., Bai, L.-P., Qi, Z.-Y., Hui, G.-Z. & Wang, Z. Overweight, obesity and meningioma risk: a meta-analysis. PloS one 9, e90167 (2014). View summary on PubMed

41. Engeland, A., Tretli, S., Hansen, S. & Bjørge, T. Height and body mass index and risk of lymphohematopoietic malignancies in two million Norwegian men and women. American journal of epidemiology 165, 44–52 (2007). View summary on PubMed

44. Larsson, S. C. & Wolk, A. Body mass index and risk of multiple myeloma: a meta-analysis. International journal of cancer. Journal international du cancer 121, 2512–6 (2007). View summary on PubMed

45. Wallin, A. & Larsson, S. C. Body mass index and risk of multiple myeloma: a meta-analysis of prospective studies. European journal of cancer (Oxford, England : 1990) 47, 1606–15 (2011). View summary on PubMed

46. Larsson, S. C. & Wolk, A. Obesity and risk of non-Hodgkin’s lymphoma: a meta-analysis. International journal of cancer. Journal international du cancer 121, 1564–70 (2007). View summary on PubMed

47. Larsson, S. C. & Wolk, A. Body mass index and risk of non-Hodgkin’s and Hodgkin's lymphoma: a meta-analysis of prospective studies. European journal of cancer (Oxford, England : 1990) 47, 2422–30 (2011). View summary on PubMed

48. Schouten, L. J. et al. Height, body mass index, and ovarian cancer: a pooled analysis of 12 cohort studies. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 17, 902–12 (2008). View summary on PubMed

49. Larsson, S. C. & Wolk, A. Body mass index and risk of multiple myeloma: a meta-analysis. International journal of cancer. Journal international du cancer 121, 2512–6 (2007). View resource

51. Larsson, S. C. & Wolk, A. Obesity and risk of non-Hodgkin’s lymphoma: a meta-analysis. International journal of cancer. Journal international du cancer 121, 1564–70 (2007). View summary on PubMed

 

 

 

The way that fat is distributed around the body can also affect the risk of cancer. ‘Apple-shaped’ people who put on weight around their stomach may have higher risks than ‘pear-shaped’ people who put on weight around their hips [35].

Scientists measure belly fat using either waist circumference (the length of tape that goes around your waist) or waist-to-hip ratio (how wide your waist is compared to your hips) [35]. Studies have found that people with larger waists or waist-to-hip ratios have higher risks of breast cancer [52], bowel cancer in men and women [24, 26], kidney cancer [53], and pancreatic cancer [34, 54].

References

24. Pischon, T. et al. Body size and risk of colon and rectal cancer in the European Prospective Investigation Into Cancer and Nutrition (EPIC). Journal of the National Cancer Institute 98, 920–31 (2006). View summary on PubMed

26. Dai, Z., Xu, Y.-C. & Niu, L. Obesity and colorectal cancer risk: a meta-analysis of cohort studies. World journal of gastroenterology : WJG 13, 4199–206 (2007). View summary on PubMed

34. Aune, D. et al. Body mass index, abdominal fatness and pancreatic cancer risk: a systematic review and non-linear dose-response meta-analysis of prospective studies. Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 23, 843–52 (2012). View summary on PubMed

35. World Cancer Research Fund/ American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. 537 (AICR, 2007). View resource

52. Connolly, B. S. et al. A meta-analysis of published literature on waist-to-hip ratio and risk of breast cancer. Nutrition and cancer 44, 127–38 (2002). View summary on PubMed

54. Stolzenberg-Solomon, R. Z. et al. Adiposity, physical activity, and pancreatic cancer in the National Institutes of Health-AARP Diet and Health Cohort. American journal of epidemiology 167, 586–97 (2008). View summary on PubMed

Obesity most likely increases the risk of cancer by raising levels of hormones such as oestrogen and insulin [55, 56].

In early life, oestrogen is mainly produced by a woman’s ovaries, but this stops after menopause. Instead, fat in the body becomes the main source of oestrogen and obese women have up to twice as much oestrogen as women with a healthy weight [57]. They also have lower levels of SHBG, or ‘sex hormone binding globulin’, which mops up oestrogen in the body [55, 58]. This is almost certainly why obesity increases the risk of breast and womb cancers [55, 58-60].

Obesity also increases levels of insulin in the body [55, 61]. It’s not clear how this could lead to cancer, although high insulin levels are a common feature of many cancers. High insulin levels could explain why being obese increases the risk of liver [43], womb [62], bowel [63], kidney [53] and pancreatic cancer [64].

Obesity could also cause cancer through other means, including:

  • Increasing the risk of oesophageal and gastric cardia cancers by causing ‘gastric acid reflux’, a condition where the stomach’s acids are briefly pushed back into the throat [65]. This damages the lining of the oesophagus and the area where it connects to the stomach.
  • Increasing the risk of gallstones, which in turn increase the risk of gallbladder cancer [38].
  • Being associated with physical inactivity or unhealthy diets.

References

38. Larsson, S. C. & Wolk, A. Obesity and the risk of gallbladder cancer: a meta-analysis. British journal of cancer 96, 1457–61 (2007). View summary on PubMed

43. Chen, Y., Wang, X., Wang, J., Yan, Z. & Luo, J. Excess body weight and the risk of primary liver cancer: an updated meta-analysis of prospective studies. European journal of cancer (Oxford, England : 1990) 48, 2137–45 (2012). View summary on PubMed

53. Luo, J. et al. Body size, weight cycling, and risk of renal cell carcinoma among postmenopausal women: the Women’s Health Initiative (United States). American journal of epidemiology 166, 752–9 (2007). View summary on PubMed

55. De Pergola, G. & Silvestris, F. Obesity as a major risk factor for cancer. Journal of obesity 2013, 291546 (2013). View summary on PubMed

56. Louie, S. M., Roberts, L. S. & Nomura, D. K. Mechanisms linking obesity and cancer. Biochimica et biophysica acta 1831, 1499–508 (2013). View summary on PubMed

57. Huang, Z. et al. Dual effects of weight and weight gain on breast cancer risk. JAMA : the journal of the American Medical Association 278, 1407–11 (1997). View summary on PubMed

58. Key, T. J. et al. Body mass index, serum sex hormones, and breast cancer risk in postmenopausal women. Journal of the National Cancer Institute 95, 1218–26 (2003). View summary on PubMed

59. Hankinson, S. E. et al. Plasma sex steroid hormone levels and risk of breast cancer in postmenopausal women. Journal of the National Cancer Institute 90, 1292–9 (1998). View summary on PubMed

60. Kaaks, R., Lukanova, A. & Kurzer, M. S. Obesity, endogenous hormones, and endometrial cancer risk: a synthetic review. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 11, 1531–43 (2002). View summary on PubMed

62. Wang, T. et al. A prospective study of inflammation markers and endometrial cancer risk in postmenopausal hormone nonusers. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 20, 971–7 (2011). View summary on PubMed

63. Jenab, M. et al. Serum C-peptide, IGFBP-1 and IGFBP-2 and risk of colon and rectal cancers in the European Prospective Investigation into Cancer and Nutrition. International journal of cancer. Journal international du cancer 121, 368–76 (2007). View summary on PubMed

Studies have shown that overweight and obese people are more likely to develop cancer than people with a healthy body weight [55, 56]. It therefore makes sense that losing weight can help to reduce the risk of cancer. It is difficult to design studies to confirm this, but some large studies have found that losing weight can help reduce the risk [66-70].

One study found that women who lost 20 pounds or more had 11% lower risks of cancer overall compared to women who had never lost that much weight 67. Another study found that women who lost 10kg since menopause, and kept the weight off, more than halved their risk of breast cancer 68. Other studies have found similar results for breast and other types of cancer [69, 70].

A review of many studies found that, overall, that the risk of cancer is lower for people that intentionally lose weight, compared to those who don’t [71].

When people try to lose weight through short-term fixes, in most cases, they end up putting the weight back on [72]. It’s unclear how this ‘weight cycling’ affects the risk of cancer.

One study found that women whose weight had gone up and down by over 10 pounds, more than ten times, had higher risks of kidney cancer than those whose weight was stable [53]. Another study found that in women that had ever had a BMI of 30 or higher, those that lost and gained 9 kg or more at least once were nearly three times more likely to develop womb cancer [73]. And there are indications that it may also increase the risk of non-Hodgkin’s lymphoma [72].

While weight cycling is a new area of research and only a few types of cancer have been studied, it does suggest that the best way to reduce the risk of cancer is to maintain a healthy bodyweight over time.

References

53. Luo, J. et al. Body size, weight cycling, and risk of renal cell carcinoma among postmenopausal women: the Women’s Health Initiative (United States). American journal of epidemiology 166, 752–9 (2007). View summary on PubMed

55. De Pergola, G. & Silvestris, F. Obesity as a major risk factor for cancer. Journal of obesity 2013, 291546 (2013). View summary on PubMed

56. Louie, S. M., Roberts, L. S. & Nomura, D. K. Mechanisms linking obesity and cancer. Biochimica et biophysica acta 1831, 1499–508 (2013). View summary on PubMed

66. Sjöström, L. et al. Effects of bariatric surgery on cancer incidence in obese patients in Sweden (Swedish Obese Subjects Study): a prospective, controlled intervention trial. The Lancet Oncology 10, 653–62 (2009). View summary on PubMed

67. Parker, E. D. & Folsom, A. R. Intentional weight loss and incidence of obesity-related cancers: the Iowa Women’s Health Study. International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity 27, 1447–52 (2003). View summary on PubMed

68. Harvie, M. et al. Association of gain and loss of weight before and after menopause with risk of postmenopausal breast cancer in the Iowa women’s health study. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 14, 656–61 (2005). View summary on PubMed

69. Eng, S. M. et al. Body size changes in relation to postmenopausal breast cancer among women on Long Island, New York. American journal of epidemiology 162, 229–37 (2005). View summary on PubMed

70. Rodriguez, C. et al. Body mass index, weight change, and risk of prostate cancer in the Cancer Prevention Study II Nutrition Cohort. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 16, 63–9 (2007). View summary on PubMed

71. Birks, S., Peeters, A., Backholer, K., O’Brien, P. & Brown, W. A systematic review of the impact of weight loss on cancer incidence and mortality. Obesity reviews : an official journal of the International Association for the Study of Obesity 13, 868–91 (2012). View summary on PubMed

72. Thompson, H. J. & McTiernan, A. Weight cycling and cancer: weighing the evidence of intermittent caloric restriction and cancer risk. Cancer prevention research (Philadelphia, Pa.) 4, 1736–42 (2011). View summary on PubMed

73. Nagle, C. M. et al. Impact of weight change and weight cycling on risk of different subtypes of endometrial cancer. European journal of cancer (Oxford, England : 1990) 49, 2717–26 (2013). View summary on PubMed

Eating habits established in childhood  often endure after many years. In 1993, a group of scientists showed that at least half of obese children were still obese as adults [74]. And a more recent study in Finland recorded children’s weight or BMI at 5 months, 1 year, ages 2-5, and finally at age 31 [75]. 

They found that children with the highest BMI from the age of 3 were over three times more likely to be obese. Another study of Scottish and English children found that people who are obese as children have higher risks of some cancers later on in life [76].

References

74. Serdula, M. K. et al. Do obese children become obese adults? A review of the literature. Preventive medicine 22, 167–77 (1993). View summary on PubMed

75. Graversen, L. et al. Preschool weight and body mass index in relation to central obesity and metabolic syndrome in adulthood. PloS one 9, e89986 (2014). View summary on PubMed

76. Jeffreys, M., Smith, G. D., Martin, R. M., Frankel, S. & Gunnell, D. Childhood body mass index and later cancer risk: a 50-year follow-up of the Boyd Orr study. International journal of cancer. Journal international du cancer 112, 348–51 (2004). View summary on PubMed

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