Weight Management After Cancer

Whilst weight loss is a well-known effect of many late-stage cancers, weight gain is very common during breast cancer treatment. In fact, most of the research on weight gain during and after treatment is focused on breast cancer, so this article refers to breast cancer frequently. However, many of the principles around losing weight gained after a cancer diagnosis are also true for other cancer types.

Somewhat surprisingly, the reasons why breast cancer and its treatment in particular cause weight gain are not fully understood. However, factors which could be involved include(1, 2):

• Decreased exercise and an increase in inactivity during chemotherapy, hormone therapy, and following active treatment

• Metabolic changes caused by the drop in oestrogen if treatment causes menopause, or by the further reduction in oestrogen caused by endocrine therapy

• Metabolic changes due to sleep disturbances (which can be linked to hot flushes / night sweats, prescribed steroids, or anxiety)

• Steroid-induced weight gain

An increase in fat mass can lead to increased oestrogen levels because fat cells can produce oestrogen via aromatisation. In addition, “fat around the middle” in particular is inflammatory. After a cancer diagnosis, an increase in fat mass and a reduction in muscle mass are associated with increased risks of cardiovascular disease and diabetes, so weight management important for health as well as aesthetic reasons.

Recent research suggests that women who gain weight during breast cancer treatment find weight loss more difficult than women who have not gained weight during treatment(3). Even weight loss using antiobesity medications (commonly referred to as “weight loss injections”) is more difficult for women taking aromatase inhibitors after a breast cancer diagnosis than it is for women who have not had breast cancer(4).

This might seem incredibly unfair! However, what it indicates to me is firstly that you should not beat yourself up mentally if you have gained weight during breast cancer treatment and struggled to lose it afterwards, as this is very common. Secondly, while weight loss is possible, it takes longer and is likely to require a more sustained effort than it would for women who have not been through breast cancer. This means that crash diets are unlikely to be successful. Any approach that you take towards losing weight needs to be a long term one, and this means that it needs to be sustainable, not overly restrictive, and not likely to lead to nutrient deficiencies.

Weight loss, or metabolic health?

If weight loss takes a long time, it can often be hard to stay motivated. It can be more motivating to focus on improvements in your health as you modify your diet and work on physical activity. Building muscle mass, feeling more energetic, reducing food cravings and sleeping better tend to be changes that women notice before they notice weight loss. These are all signs of improved metabolic health, and are just as valuable (if not more so) than a number on the scales.

When it comes to numbers on scales, you may not notice so much weight loss if you trying to lose weight whilst also increasing your muscle mass through strength training. Your waist circumference and/or your waist to height ratio are often considered better indicators of health than weight or BMI. For a reduced risk of metabolic conditions, a woman’s waist circumference should be less than 88cm, and if you divide your waist circumference by your height, you should get a figure below 0.5.

Protein

It might seem paradoxical to begin dietary advice on weight loss by inviting you to think about whether you are eating enough protein, but keep reading! The Protein Leverage Hypothesis is a theory that the human need and appetite for dietary protein is so strong that if we do not get enough protein from our diet, we are driven to keep eating more and more of whatever lower protein foods we are eating in an attempt to get enough protein to meet our needs. In other words, appetite for protein drives our overall appetite.

The hormone changes of menopause result in a net breakdown of the proteins in the body, such as loss of muscle and bone mass, yet it is very important to maintain as much muscle and bone mass as possible. The amount of dietary protein we need to avoid loss of muscle and bone mass increases in menopause. It is estimated that a combination of mild calorie restriction and an increase in protein intake would result in more effective weight loss(5).

Ensuring that your daily protein requirement is evenly spread throughout the day, or even front-loaded so that you eat more at breakfast than at dinnertime, is a very effective way of staying full and avoiding cravings. Aiming for at least 20g of protein at breakfast time is helpful for many women, and some women will need more than this. All the breakfast recipes in this month’s recipe book contain at least 20g of protein. The following table lists the protein content of some common high foods.

Protein content in foods

Combined with strength training, eating enough protein will support muscle maintenance or even growth, which is supportive of good metabolic health.

Proportions of foods on your plate

Whilst a degree of calorie restriction is important for weight loss, it can be tiresome to keep counting calories long term, and can also lead to an unhealthy relationship with food. I prefer to focus on eating enough of the foods that will naturally keep you feeling full without leading to overconsumption of calories. The following plate image, produced by the British Association for Nutrition and Lifestyle Medicine, is a useful guide to eating in order to achieve weight loss in a sustainable way.

Note that half the plate is made up of non-starchy vegetables; greens and brightly colours. The fibre from these helps to keep you feeling full. More than a quarter of the plate is taken up by protein, reflecting what we have discussed above. Only the remainder (less than a quarter of the plate) is made up of foods high in starchy carbohydrates, such as whole grains and root vegetables. All grains should be in their whole form (brown rice, jumbo oats etc) if you want to lose weight, as they do not raise blood sugar as much as white, refined grains.

Have a read of the “Avoid” section on this graphic. Sweets, cakes, biscuits, sugary drinks and even bread are best avoided if you want to lose weight.

Including smaller amounts of healthy fats is still important for their anti-inflammatory and nutritional benefits. These include extra virgin olive oil, avocados, oily fish and nuts and seeds.

BANT Rainbow Plate

One final point on eating for sustained weight loss is that it’s best to avoid snacking completely if at all possible. Eating three meals per day rather than two is likely to make it easier to obtain your protein requirements, but you do not need more than this. If you currently find it difficult to get from one meal to the next without a snack, then try structuring your meals according to the plate image above and you should start to find it easier, particularly if you are eating enough protein.

Time to Eat?

Many women try fasting in various forms in an attempt to lose weight. If you have recently been put into menopause, or if your menopause has recently been made more severe by aromatase inhibitors, then fasting should be approached with caution, and with the understanding that it is a stress on the body at a time when the body is already subject to a lot of stress.

Stress can be a key factor that prevents weight loss. The release of stress hormones results in a cascade of events which culminates with fat being deposited around the middle – exactly where we don’t want it! Over time, stress also results in insulin resistance, which means that a given amount of carbohydrate is more likely to result in weight gain. Of course, stress also leads to fatigue and reduced physical activity.

We may think of stress as being mental or emotional, but physical stresses result in just the same patterns in the body. The menopause transition is stressful for the body(6); add a cancer diagnosis into the mix and there are likely to be even higher levels of circulating stress hormones! Fasting is a stressor too. Stressors can be helpful if they are mild, but long fasts may be counterproductive.

An overnight fast of around 13-14 hours is feasible for most women without being too stressful. This could mean finishing dinner at 6pm and not eating or drinking anything calorific until 8am the following morning. For a given eating window, it is better to start and finish eating earlier in the day, as humans become more insulin resistant as the day goes on.

Sleep

We have covered the ways in which stress can result in weight gain, particularly “fat around the middle”. Sleep is another important lifestyle factor when it comes to weight loss. We know that even minor sleep deprivation results in increased appetite and poorer food choices the following day. It also increases insulin resistance(7, 8).

In Summary

Weight gain during breast cancer treatment is common, and losing that weight can be challenging and may take longer than you expect. Many women may not return to their pre-cancer weight or shape, and this is normal too, particularly if treatment has caused menopause. The menopause results in a redistribution of body fat, with increased fat around the middle. Whilst this may be expected if menopause occurs at a normal age, it can be challenging to accept if you have been put into an early menopause.

Working on building muscle and bone mass, through strength training and eating enough protein, can be a helpful way to shift your focus and see faster results whilst still having major benefits for your current and future health. Waist measurements, or even how your clothes fit, are just as valid as the scales for assessing your progress.

Focus on eating adequate protein and a large rainbow of non-starchy vegetables. Make sure that all your carbohydrate containing foods are in their whole forms, and limit the quantity to less than a quarter of your plate per meal (I often refer to this as about a cupped handful). Refer to the graphic above for those foods that are best avoided….you know what they are!

Eat three meals per day but avoid snacking. Allow an overnight fast of 13-14 hours, and keep your eating window earlier in the day rather than later.

If weight loss isn’t happening, don’t forget to consider stress management and getting enough good quality sleep.

Above all, be kind and patient with yourself – your body has got you through a lot!

References

(1)   Makari-Judson, G., Braun, B., Jerry, D.J. et al. (2014). ‘Weight gain following breast cancer diagnosis: Implication and proposed mechanisms’, World Journal of Clinical Oncology, 5(3), 272-282. Available at https://pmc.ncbi.nlm.nih.gov/articles/PMC4127600/

(2)   Ee, C., Cave, A., Vaddiparthi, V. et al. (2023). ‘Factors associated with weight gain after breast cancer: Results from a community-based survey of Australian women’, The Breast, 69, 491-498. Available at https://pmc.ncbi.nlm.nih.gov/articles/PMC10300610/

(3)   Hoobler, R., Puklin, L.S., Harrigan, M. et al. (2024). ‘Baseline predictors associated with successful weight loss among breast cancer survivors in the Lifestyle, Exercise, and Nutrition (LEAN) study’, Journal of Cancer Survivorship: Research and Practice, (2024). Available at https://pubmed.ncbi.nlm.nih.gov/39528779/

(4)   Fansa, S., Ghusn, W., Tama, E. et al. (2024). ‘Efficacy of antiobesity medications among breast cancer survivors taking aromatase inhibitors’, Breast Cancer Research and Treatment, 208(3), 553-563. Available at https://pubmed.ncbi.nlm.nih.gov/39080119/

(5)   Simpson, S.J., Raubenheimer, D., Black, K.I. et al. (2022). ‘Weight gain during the menopause transition: Evidence for a mechanism dependent on protein leverage’, BJOG: An International Journal of Obstetrics and Gynaecology, 130(1), 4-10. Available at https://obgyn.onlinelibrary.wiley.com/doi/10.1111/1471-0528.17290

(6)   Hantsoo, L., Jagodnik, K.M., Novick, A.M. et al. (2023). ‘The role of the hypothalamic-pituitary-adrenal axis in depression across the female reproductive lifecycle: current knowledge and future directions’, Frontiers in Endocrinology, 14, 1295261. Available at https://pmc.ncbi.nlm.nih.gov/articles/PMC10750128/

(7)   Antza, C., Kostopoulos, G., Mostafa, S. et al. (2021). ‘The links between sleep duration, obesity and type 2 diabetes mellitus’, the Journal of Endocrinology, 252(2), 125-141. Available at https://pmc.ncbi.nlm.nih.gov/articles/PMC8679843/

(8)   Zuraikat, F.M., Laferrère, B., Cheng, B. et al. (2024). ‘Chronic Insufficient Sleep in Women Impairs Insulin Sensitivity Independent of Adiposity Changes: Results of a Randomized Trial’, Diabetes Care, 47(1), 117-125. Available at https://pmc.ncbi.nlm.nih.gov/articles/PMC10733650/