Rethinking Obesity Treatment: Why Resistance Exercise Prescription Must Move to the Forefront
In the UK, the average lifespan is around 81 years, but the health span is significantly shorter at just 63 years, resulting in many adults spending nearly two decades in poor health. Obesity plays a major role in this decline, contributing to metabolic syndrome, cardiovascular disease, and cancer. With the UK having one of the highest obesity rates in Europe, 29% in 20221, projected to reach 36% by 20402, the strain of this epidemic on the already struggling healthcare system is undeniable. To address this, the focus must shift beyond obesity alone to key health markers. While diet remains the most effective tool for weight loss, exercise prescription, particularly resistance training, is essential for these health markers, enhancing insulin sensitivity, and preserving muscle mass during weight loss. I argue that in light of this, resistance training must be “pushed to the forefront” and integrated alongside diet in obesity management.
A Holistic Approach to Obesity Management
Is an obese person necessarily unhealthy? I'd argue not, considering how a professional rugby player may be classified as obese due to their high muscle mass despite being in peak physical health. This is a clear example of how despite being an excellent metric on an epidemiological basis, BMI has failed to account for body composition and key metabolic biomarkers essential for characterising health. Hence, the focus needs to shift away from arbitrary weight classifications and toward a more holistic approach, rather than relying solely on BMI3. This can be done by incorporating body composition metrics via DEXA scans and blood biomarkers. In research regarding dietary intervention and exercise prescription, this change has improved strategies in obesity management, enhancing metabolic health, weight loss, and overall well-being3.
The Importance of Muscle Mass for Longevity
Muscle mass is crucial for healthy ageing, particularly during the “marginal decade” (ages 60–70), where strength and function significantly decline. Hence, maintaining and building muscle strength and mass is essential to protect against sarcopenia and its consequences of frailty, falls, and dependency. This is highlighted in research showing the link between low levels of muscle mass and a higher risk of mortality (see Figure 1)4.
Additionally, low muscle mass is an independent risk factor for all-cause mortality and cardiovascular disease. This effect on mortality was even greater for those with poor metabolic health or obesity, perhaps due to muscle tissue acting as a metabolic reservoir for glucose regulation and insulin sensitivity4. This highlights the greater importance of maintaining and increasing muscle strength in those groups.
Risks of Weight Loss Without Exercise
How is weight loss achieved? Weight loss is fundamentally driven by maintaining a caloric deficit—an undeniable principle rooted in the first law of thermodynamics. However, the intricacies of the “calories in, calories out” equation go far beyond simple math and are a strongly debated topic. Ideally, weight loss would come primarily from adipose tissue. However, in a hypocaloric state, the body is efficient at breaking down understimulated muscle tissue—especially when combined with a sedentary lifestyle and inadequate protein intake. Unfortunately, this scenario is common, resulting in worsened body composition and, worst case, sarcopenic obesity. This issue has been highlighted by the popularity of pharmacological interventions like GLP-1 receptor agonists (e.g., Semaglutide), which create large caloric deficits, often composed of low-nutrient-dense foods and lack of resistance training5.
Thankfully, maintaining lean mass during weight loss is possible with the right approach. By ensuring adequate high-quality protein intake and incorporating resistance training into weight loss interventions, muscle tissue can be preserved6. Furthermore, resistance training not only helps preserve muscle mass but also enhances dietary interventions by improving body composition and markers of metabolic health such as cholesterol levels and insulin sensitivity (see Figure 2)7. Additionally, high-intensity or interval endurance training proves more effective than moderate-intensity, steady-state cardio for metabolic benefits8. This suggests that combining resistance training with high-intensity exercise and an energy deficit may be the most effective strategy for improving overall health in obese populations.
Conclusion
Diet remains the leading strategy for initial weight loss. Alone, it falls short in preserving muscle mass, improving body composition, and addressing long-term health outcomes. However, when combined with exercise, particularly resistance training, the benefits on health are enhanced and pitfalls reduced. The fight against obesity should not prioritize short-term weight loss at the expense of long-term health. We must redefine success in obesity management to include metrics beyond BMI, focusing on quality of life, metabolic health, and longevity. By looking at this issue through this lens, exercise prescription, especially resistance training, is not merely “one of the pack” in obesity management; it is the linchpin for sustainable health and well-being. It's time to move beyond solely focusing on diet, with resistance training as a cornerstone of obesity treatment and public health weight management programs.
Bibliography
- National Health Service (NHS) Digital. Health Survey for England, 2022 Part 2: Adult Overweight and Obesity. 24 Sep 2024. Available from: https://digital.nhs.uk/data-and-information/publications/statistical/health-survey-for-england/2022-part-2/adult-overweight-and-obesity
- Cancer Research UK. A new analysis estimates over 21 million UK adults will be obese by 2040. 19 May 2022. Available from: https://news.cancerresearchuk.org/2022/05/19/new-analysis-estimates-over-21-million-uk-adults-will-be-obese-by-2040/
- Gallagher D, Deurenberg P, Heymsfield SB, et al. Chapter 5: Body composition and physical activity. In: Stewart T, editor. Physical Activity and Health: An Interactive Approach. 2024. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6690141/
- McGlory C, Phillips SM. Muscle mass loss during weight loss: effects on metabolic rate and glucose metabolism. J Cachexia Sarcopenia Muscle. 2023;14(1):21-31. doi: 10.1002/jcsm.13397.
- Sztalryd C, O'Brien E, Britton C, et al. Impact of GLP-1 receptor agonist use on lean mass in obesity treatment: a randomized controlled trial. Diabetes Obes Metab. 2024;26(2):396-405. doi: 10.1111/dom.15271.
- Nowicki A, Gąsior Z, Wojciechowski J, et al. Obesity and its metabolic consequences: an updated review. Qual Soc Sci. 2024;29(2):118-126.
- Ross R, Janssen I, Dawson J, et al. Caloric restriction with or without exercise: the effect on body composition and fat distribution. Med Sci Sports Exerc. 2010;42(1):92-98. doi: 10.1249/MSS.0b013e3181b0c5d1.
- Papamichael N, Ellis C, Symonds ME. The effect of exercise on body composition and muscle mass in obesity: A systematic review. Diabetol Metab Syndr. 2015;7:45. doi: 10.1186/s40200-015-0154-1.
