This really comes down to two questions:

What do you want?

AND

What is your current body composition?

If someone is living with overweight or obesity and has a substantial amount of body fat that they would like to lose then they can probably get after it with a more rapid weight loss approach without any significant additional downsides [1-3].

Depending on someone’s personality and their initial motivation, it may even be easier to lose weight more quickly. In these scenarios, trying to curb that enthusiasm with a more gradual approach may be unwarranted and potentially even unhelpful [4].

Dieting sucks and dieting for less time can suck less.

However, if you are already relatively lean and well-muscled it is likely best to take a slower weight loss approach (~0.5% body weight per week) to potentially prevent muscle loss [5-9].

However, it is important to understand the positives and negatives of both approaches.

Contrary to current public opinion, both slow and fast strategies seem to work equally well for long-term weight loss in fat loss seeking populations [10]. On average those who lose weight quickly do not seem to be more prone to weight regain than those who lose weight more slowly [11].

Those who lose weight faster may see larger improvements in their metabolic health and may even lose more weight overall [12-16]. Also, being satisfied with one’s weight loss results seems to be a cognitive factor associated with successful long-term weight loss [17-19].

In a study by Purcell et al., 2014 [20] the gradual weight loss group that lost 15% of their body weight in 36 weeks had 27% more drop outs compared to the rapid weight loss group who lost 15% of their body weight in just 12 weeks. 

Seeing the scale move consistently and quickly can be extremely motivating for some people. But, we also have to be careful because some people can become fixated on that weight loss number and forget that an active fat loss phase is by definition NOT sustainable. 

Over the last few decades, we have learned that losing weight is the "easier" part, whereas keeping it off long-term seems to be more difficult [21]. This is why keeping the end in mind from the start and taking time to focus and cultivate the skills and habits (increased food quality, physical activity, autonomy, self-efficacy, and self-regulation abilities) that relate to long-term weight loss success is so important [22-24].

Those who lose weight more quickly with low calorie diets without exercise may be more prone to muscle and bone loss compared to those who lose weight more gradually, although the muscle loss does look to be proportional to the increased weight loss (AKA because they lose more weight they tend to lose more muscle when there isn't exercise in play) [10, 13].

I am honestly much less worried about these muscle and bone loss findings from rapid weight loss approaches in overweight/obese populations IF these individuals eat sufficient protein and resistance train. It is actually possible that overweight or obese untrained individuals can build muscle and lose body fat at the same time (covered HERE) while maintaining or even increasing their resting metabolic rate, however, we do need more research on metabolic health and hormonal markers as kcals are increased back to energy balance at their new body composition [25-27].

Another aspect to be cognizant of is that appearance-based goals and unrealistic expectations at the onset of a weight loss journey have been found to be related to a higher likelihood of attrition [18, 28].

Everyone has their reasons for why they might want to change how their body looks or feels, but in a culture that can sometimes become fixated on aesthetics it is good to remember that even maintaining a 5% weight loss will very likely increase your metabolic health and may even reduce one's risk of type 2 diabetes by 89% [29].

TL;DR - Ultimately, the speed of weight loss is up to the individual. Both rapid and gradual approaches can work. What’s most important to remember is that the work doesn’t end when the goal is reached.

REFERENCES:

1. Koliaki, C., et al., Defining the Optimal Dietary Approach for Safe, Effective and Sustainable Weight Loss in Overweight and Obese Adults. Healthcare (Basel), 2018. 6(3).

2. Tsai, A.G. and T.A. Wadden, The evolution of very-low-calorie diets: an update and meta-analysis. Obesity (Silver Spring), 2006. 14(8): p. 1283-93.

3. Saris, W.H., Very-low-calorie diets and sustained weight loss. Obes Res, 2001. 9 Suppl 4: p. 295S-301S.

4. Martin, C.K. and K.M. Gadde, Weight loss: slow and steady does not win the race. Lancet Diabetes Endocrinol, 2014. 2(12): p. 927-8.

5. Roberts, B.M., et al., Nutritional Recommendations for Physique Athletes. J Hum Kinet, 2020. 71: p. 79-108.

6. Garthe, I., et al., Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes.Int J Sport Nutr Exerc Metab, 2011. 21(2): p. 97-104.

7. Hulmi, J.J., et al., The Effects of Intensive Weight Reduction on Body Composition and Serum Hormones in Female Fitness Competitors. Front Physiol, 2016. 7: p. 689.

8. Mitchell, L., et al., Physiological implications of preparing for a natural male bodybuilding competition. Eur J Sport Sci, 2018: p. 1-11.

9. Mero, A.A., et al., Moderate energy restriction with high protein diet results in healthier outcome in women. J Int Soc Sports Nutr, 2010. 7(1): p. 4.

10. Ashtary-Larky, D., et al., Effects of gradual weight loss v. rapid weight loss on body composition and RMR: a systematic review and meta-analysis.Br J Nutr, 2020: p. 1-12.

11. Vink, R.G., et al., The effect of rate of weight loss on long-term weight regain in adults with overweight and obesity. Obesity (Silver Spring), 2016. 24(2): p. 321-7.

12. Seimon, R.V., et al., Effect of Weight Loss via Severe vs Moderate Energy Restriction on Lean Mass and Body Composition Among Postmenopausal Women With Obesity: The TEMPO Diet Randomized Clinical Trial. JAMA Netw Open, 2019. 2(10): p. e1913733.

13. Seimon, R.V., et al., 3-Year effect of weight loss via severe versus moderate energy restriction on body composition among postmenopausal women with obesity - the TEMPO Diet Trial. Heliyon, 2020. 6(6): p. e04007.

14. Wing, R.R., et al., Association of Weight Loss Maintenance and Weight Regain on 4-Year Changes in CVD Risk Factors: the Action for Health in Diabetes (Look AHEAD) Clinical Trial. Diabetes Care, 2016. 39(8): p. 1345-55.

15. Sellahewa, L., et al., A Systematic Review of Evidence on the Use of Very Low Calorie Diets in People with Diabetes. Curr Diabetes Rev, 2017. 13(1): p. 35-46.

16. Steven, S., et al., Very Low-Calorie Diet and 6 Months of Weight Stability in Type 2 Diabetes: Pathophysiological Changes in Responders and Nonresponders. Diabetes Care, 2016. 39(5): p. 808-15.

17. Dalle Grave, R., M. Sartirana, and S. Calugi, Personalized cognitive-behavioural therapy for obesity (CBT-OB): theory, strategies and procedures. Biopsychosoc Med, 2020. 14: p. 5.

18. Dalle Grave, R., S. Calugi, and G. Marchesini, The influence of cognitive factors in the treatment of obesity: Lessons from the QUOVADIS study. Behav Res Ther, 2014. 63: p. 157-61.

19. Montesi, L., et al., Long-term weight loss maintenance for obesity: a multidisciplinary approach. Diabetes Metab Syndr Obes, 2016. 9: p. 37-46.

20. Purcell, K., et al., The effect of rate of weight loss on long-term weight management: a randomised controlled trial. Lancet Diabetes Endocrinol, 2014. 2(12): p. 954-62.

21. Wing, R.R. and S. Phelan, Long-term weight loss maintenance. Am J Clin Nutr, 2005. 82(1 Suppl): p. 222S-225S.

22. Varkevisser, R.D.M., et al., Determinants of weight loss maintenance: a systematic review. Obes Rev, 2019. 20(2): p. 171-211.

23. Teixeira, P.J., et al., Successful behavior change in obesity interventions in adults: a systematic review of self-regulation mediators.BMC Med, 2015. 13: p. 84.

24. Spreckley, M., J. Seidell, and J. Halberstadt, Perspectives into the experience of successful, substantial long-term weight-loss maintenance: a systematic review. Int J Qual Stud Health Well-being, 2021. 16(1): p. 1862481.

25. Longland, T.M., et al., Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. Am J Clin Nutr, 2016. 103(3): p. 738-46.

26. Bryner, R.W., et al., Effects of resistance vs. aerobic training combined with an 800 calorie liquid diet on lean body mass and resting metabolic rate. J Am Coll Nutr, 1999. 18(2): p. 115-21.

27. Ross, R., et al., Exercise-induced reduction in obesity and insulin resistance in women: a randomized controlled trial. Obes Res, 2004. 12(5): p. 789-98.

28. Dalle Grave, R., et al., Weight loss expectations in obese patients and treatment attrition: an observational multicenter study. Obes Res, 2005. 13(11): p. 1961-9.

29. Uusitupa, M., et al., Prevention of Type 2 Diabetes by Lifestyle Changes: A Systematic Review and Meta-Analysis. Nutrients, 2019. 11(11).