For many of my patients it’s so disheartening to stand on the scales and not see any improvement despite their best efforts to adapt positive lifestyle changes. They are told to eat less and move more, but doing so makes no difference. Alternatively, they can lose weight through changes in diet or exercise but find within a short time of going back to a normal lifestyle, they are back where they started or at an even higher weight. These cycles often lead to frustration and helplessness.
What we now know through research is that the body views weight loss as a threat and has metabolic adaptations to try to regain the weight. Two of the main mechanisms are discussed below.
Hormones and Appetite
There are many hormones involved in appetite regulation. Two of these are leptin and ghrelin. Leptin is a hormone that signals satiety, or the feeling of fullness and ghrelin is a hormone which stimulates hunger. When weight is lost, the levels of leptin decrease and the levels of ghrelin increase.1,2 This causes an involuntary increase in hunger that patients can experience even 12 months down the track, including if all the lost weight has been regained.1,2
Studies have also shown that when individuals go through a period of calorie restriction the body reduces its energy expenditure beyond what would be expected for the lower body weight.2 This means to maintain the same weight, an individual would have to further reduce their calorie intake. This adaptation also persists for months or even years after the initial period of weight loss, which not only increases the risk of weight gain, but also makes future weight loss attempts even harder.2
So, in summary, when you lose weight, the body sends out signals that result in you feeling hungrier while simultaneously reducing the energy you are burning off. This is not a personal choice or a failure of willpower, but a physiological response. A lot of different factors influence weight (a topic for another day), so for some people this can be overcome with ongoing changes to diet and exercise, but for others it leads to regaining the weight and starting the cycle again. It is frustrating but unfortunately, Obesity is a chronic disease, and for many people, it requires a comprehensive sustainable management plan to counteract this physiological response.
If you are struggling with your weight then please book in with a GP trained in weight management to discuss your individual circumstances.
References:
- Sumithran P. et al. Long-term Persistence of Hormonal Adaptation to Weight Loss, New England Journal of Medicine 2011 365:1597-604
- Rosenbaum M et al; Adaptive thermogenesis in humans; Int J Obes (Lond). 2010 Oct; 34(0 1): S47–S55.
