Low energy intake and minimal body fat are perceived as indicators of energy unavailability, resulting in a homeostatic endocrine response aimed at conserving energy and promoting energy intake.
When we restrict energy (Calories) from our bodies for an extended period of time we are accompanied by a host of changes in our circulating hormones, mitochondrial efficiency, and energy expenditure
A general endocrine response to hypocaloric (Low calorie) diets are increased hunger, reductions in metabolic rate, and the maintenance of lean mass is compromised
Basically your body does not care about your vanity and when we lose weight by cutting calories, you expend less energy and don’t need to consume as many to maintain weight either this is referred to as adaptive thermogenesis
Numerous Studies involving energy restriction report decreases in leptin , insulin , testosterone, and thyroid hormones. Whilst subsequently, increasing ghrelin and cortisol.
These unfavorable changes in hormone levels persist long after desired weight has been reached making it harder for long term weight maintenance.
A study took –
50 overweight and/or obese patients without diabetes in a 10-week weight-loss program for which a very-low-energy diet was prescribed. circulating levels of hormones such as Leptin & Ghrelin, Insulin as well as other key hormones and participants rating of appetite were all measured. They were measured At baseline (before weight loss), at 10 weeks , and at 62 weeks (both after program completion.)
Findings show that One year after initial weight reduction, levels of the circulating mediators of appetite that encourage weight regain after diet-induced weight loss did not revert to the levels recorded before weight loss
In some people there is also an increase in Lipoprotein Lipase enzyme which is responible for removing Lipids from the blood and into stroage. So when normal eating resumes fat storage becomes enhanced.
Not to mention that an 8 -12 week fat loss program are going to be super restrictive and hard work after you have reached the desired goal normal response would be to binge on all the things you’ve sacrificed and you’re probaly not going to want to exercise for a while either coupled with the increase in hunger hormones
The question is are short term restrictive diets worth it?