Why does your diet keep failing?

blog corporate health & wellbeing weight inclusivity weight management workplace wellbeing May 24, 2024

Unfortunately, weight cycling is common for many people who go on extreme or fad diets, and it also has a negative impact on cardiometabolic health [1]. They find themselves losing weight initially, but then in more cases than not, they gain the weight back along with a little bit extra. Is it you to blame for these failures, or is it your biology? The evidence points to the latter.

One reason your diet may be failing is that fad diets commonly restrict foods or entire food groups such as carbohydrates (such as the keto diet). It’s common for people to see initial weight loss when reducing carbohydrates, but this is a result of reduced water weight - not fat loss. Most of these diets are designed for the short-term, in that they are rigid and require an enormous amount of mental energy and time which is unsustainable in the long-term [2].

Another reason is to do with your hunger hormones. Back in hunter-gatherer days, food was not as readily accessible as it is in our society now. It made sense for our bodies to slow down during times of deprivation to avoid fat loss. We still have these same mechanisms today! Your metabolism slows down and you begin to burn less energy at rest when you are in an extreme deficit [3]. This lowered metabolism is one reason why people tend to put more weight back on once their diet returns to normal after a period of extreme dieting. Additionally, appetite hormones increase, making it more difficult to sustain a period of restrictive dieting [4]. Clearly, there is more to the story than a lack of willpower.

Changing our habits is the only proven method for achieving our goals in the long term - Dr Gina Cleo (The Habit Revolution).

So, what can you do instead? Instead of taking the rapid weight loss approach, you can focus on building healthy habits into your life that are realistic for you. This may lead to slower weight loss, but you are more likely to keep the weight off in the long-term. Our dietitians are habit-change experts, and can help you break unhealthy habits and replace them with healthy ones to help you lose weight for good!


[1] Oh TJ, Moon JH, Choi SH, Lim S, Park KS, Cho NH, et al. Body-Weight Fluctuation and Incident Diabetes Mellitus, Cardiovascular Disease, and Mortality: A 16-Year Prospective Cohort Study. J Clin Endocrinol Metab 2018. https://doi.org/10.1210/jc.2018-01239.

[2] Tahreem A, Rakha A, Rabail R, Nazir A, Socol CT, Maerescu CM, et al. Fad Diets: Facts and Fiction. Front Nutr 2022. https://doi.org/10.3389/fnut.2022.960922.

[3] Busetto L, Bettini S, Makaronidis J, Roberts CA, Halford JCG, Batterham RL. Mechanisms of weight regain. Eur J Intern Med 2021. https://doi.org/10.1016/j.ejim.2021.01.002.

[4] Thom G, McIntosh A, Messow CM, Leslie WS, Barnes AC, Brosnahan N, et al. Weight loss-induced increase in fasting ghrelin concentration is a predictor of weight regain: Evidence from the Diabetes Remission Clinical Trial (DiRECT). Diabetes, Obes Metab 2021. https://doi.org/10.1111/dom.14274.