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Debate continues into how the rate of weight loss might affect the long-term efficacy of a weight-loss programme. For many years, most experts in nutrition argued that rapid weight loss is always followed by rapid weight regain, and perhaps even to a higher weight than before dieting.

Fortunately, we now have a considerable volume of evidence that disproves this pessimistic outlook. In the latter part of the last century, clinical trials started to reveal how it really wasn’t the rate of weight loss that determined the rate or extent of weight regain, but rather the general approach to obesity that mattered.

Let’s have a look at some of the findings:

  1.  The final weight loss that is typically achieved with a diet programme appears to be strongly related to the amount of weight you lose in the initial 3 to 8 weeks. (Refs 1-3)
  2.  Rapid weight loss maintains motivation, evidenced by the fact that more individuals drop out of slow weight loss programmes than rapid ones. (Ref 4)
  3. The total weight loss is greater with a rapid weight loss programme than with slow weight loss. (Ref 2)
  4. The metabolic benefits (blood glucose control, improved blood fats) are more closely linked to the total weight loss than to the rate of weight loss (though the nutrient balance is also important). (Ref 5)
  5. Weight regain does not differ between groups of patients in slow weight loss programmes and rapid weight loss. (Ref 6)
  6. Prof Susan Jebb (University of Oxford and member of the Public Health England Obesity Programme Board), among others, has described how the harm done by overweight and obesity depends on the total time an individual spends in that situation. This is logical: the sooner we reduce the risk of obesity-related chronic diseases, such as diabetes or heart disease, the better.7 And even if weight gradually returns, the time spent out of the obese weight range has ben shown to have a lasting benefit. The US Diabetes Prevention Trial showed that even after temporary weight loss, a reduction in the risk of diabetes persisted for at least 15 years. (Ref 8)

The conclusions we can draw from the findings of these research studies are the following:

  •  Rapid weight loss appears to be more effective in both the short term and the long term.
  •  More individuals are likely to achieve their weight-loss goal with rapid weight loss.
  • The health benefits are likely to be greater with rapid weight loss (because of the greater weight loss)
  • Whatever approach is used to achieve weight loss, additional measures are essential to prevent weight regain.

What does this all mean for you if you need to lose weight?

Everyone is different and the approach to weight loss must be individualised. As health professionals working in weight management, first we must be able and willing to discuss and explain the multiple options available to you and help you find the one most likely to work for you based on the aetiology of your weight gain and on your current state of health. And second, any proposed weight management programme must include a plan to avoid weight regain. Without this second part, all your investment (economic and your personal effort) is likely to be wasted.

A programme that fulfils the above requirements necessitates a multidisciplinary approach, with medical supervision (health and safety, goal setting, weight-loss method), dietitian/nutritionist (diet design, nutrient balance), personal trainer (physical activity), psychologist/therapist (motivation and relationship with food). Not all these disciplines are needed in every case, but they must be available when necessary.


  1. Clinical Correlates of Weight Loss and Attrition During a 10-Week Dietary Intervention Study: Results from the NUGENOB Project. Obesity Facts (The Eur J of Obesity) 2012;5:928–936. https://www.karger.com/Article/FullText/345951
  2. Obesity treatment by very low-calorie-ketogenic diet at two years: reduction in visceral fat and on the burden of disease. Endocrine. https://link.springer.com/article/10.1007/s12020-016-1050-2
  3. Initial weight loss on an 800-kcal diet as a predictor of weight loss success after 8 weeks: the Diogenes study. European Journal of Clinical Nutrition 2010;64:994–999 https://www.nature.com/articles/ejcn2010110
  4. Predictors of attrition and weight loss success: Results from a randomized controlled trial. Behaviour Research and Therapy, 2009. https://europepmc.org/article/PMC/2713356
  5. Absolute weight loss, and not weight loss rate, is associated with better improvements in metabolic health. The Obesity Journal; Vol 2019: https://www.hindawi.com/journals/jobe/2019/3609642/
  6. The Association Between Rate of Initial Weight Loss and Long-Term Success in Obesity Treatment: Does Slow and Steady Win the Race? International Journal of Behavioural Medicine, 2010;17: 161-167. https://link.springer.com/article/10.1007%2Fs12529-010-9092-y
  7. The number of years lived with obesity and the risk of all-cause and cause-specific mortality. Int. J. Epidemiol 2011;40:985–996 https://academic.oup.com/ije/article/40/4/985/681646
  8. Diabetes Prevention Program Research Group. Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications over 15-year follow-up: The Diabetes Prevention Program Outcomes Study. The Lancet Diabetes & Endocrinology 2015;3(11):866–875. https://www.thelancet.com/journals/landia/article/PIIS2213-8587(15)00291-0/fulltext