Losing weight is often presented as a simple equation: eat less, move more, lose weight. But anyone who has tried to maintain significant weight loss knows that the reality is much more complicated. For many people, the difficult part is not losing the weight. It is keeping it off.
Weight regain is common, and it is often interpreted as a failure of motivation or willpower. However, research tells us that our biology actively changes when we lose weight, making long-term weight maintenance more challenging. Understanding these changes is important because it changes the way we think about weight management.
A number of physiological adaptations occur in response to weight loss. Energy expenditure decreases, appetite increases, and hormonal signals involved in hunger and satiety change. These adaptations are thought to be part of the body's attempt to restore energy balance. In other words, the body does not necessarily recognise weight loss as the end goal. It may respond by encouraging us to eat more and conserve energy.
Two hormones that help explain this response are ghrelin and leptin. Ghrelin is produced primarily in the stomach and is involved in stimulating appetite. Following weight loss, ghrelin levels may increase, contributing to increased hunger. Leptin is produced by adipose tissue and provides the brain with information about the body's energy stores. As body fat decreases, leptin levels also fall. These changes can make maintaining a lower body weight physiologically difficult.
Weight loss also reduces the amount of energy the body requires. A smaller body naturally requires less energy to maintain and move. However, research has also demonstrated adaptive thermogenesis, where energy expenditure can decrease beyond what would be expected from changes in body size alone. The result is that someone who has lost weight may require fewer calories to maintain their new weight than they did before. This can make the same diet that initially produced weight loss increasingly difficult to sustain.
We also live in an environment where highly processed, energy-dense foods are readily available, portion sizes are often large, and opportunities for physical activity may be limited. Stress and inadequate sleep can further influence appetite, food choices and metabolic health. This means that maintaining weight loss requires someone to navigate both biological adaptations and an environment that promotes weight gain.
If weight regulation were purely behavioural, maintaining weight loss would be much easier. Instead, it is influenced by an interaction between:
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Biology
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Behaviour
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Environment
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Sleep
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Stress
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Physical activity
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Food environment
This is also why repeated cycles of restrictive dieting may not be the most effective long-term strategy. The goal should not simply be to lose weight as quickly as possible. It should be to develop sustainable changes that support metabolic health over time.
The same principle is relevant when we consider pharmacological treatment. Medications such as GLP-1 receptor agonists can influence appetite and other metabolic pathways, making weight loss more achievable for many people. However, studies have shown that weight regain can occur after treatment is discontinued. This does not mean that these medications are ineffective. Rather, it reflects the chronic nature of obesity and the biological mechanisms involved in weight regulation.
At Remisi, we look beyond the initial reduction in body weight. We consider the factors that influence long-term metabolic health:
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Nutrition
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Movement
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Sleep
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Stress
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Social connection
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Behavioural patterns
We also look at meaningful clinical outcomes such as HbA1c, blood glucose, blood pressure, waist circumference and other markers of metabolic health. Because the objective is not simply to make the number on the scale smaller. It is to improve the health of the person behind the number.
References
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Sumithran P, et al. (2011). Long-term persistence of hormonal adaptations to weight loss. New England Journal of Medicine.
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Rosenbaum M, Leibel RL. (2010). Adaptive thermogenesis in humans. International Journal of Obesity.
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Hall KD, Kahan S. (2018). Maintenance of lost weight and long-term management of obesity. Medical Clinics of North America.
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Rubino D, et al. (2021). Effect of continued weekly subcutaneous semaglutide vs placebo on weight loss maintenance. JAMA.
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Lean MEJ, et al. (2018). Primary care-led weight management for remission of type 2 diabetes (DiRECT). The Lancet.
