Can Gradually Increasing Calories Boost Metabolism and Prevent Weight Regain?

What is Reverse Dieting?

Obesity is a prevalent health problem, and consequently about half of the population reports wanting to lose weight on any given day. However, sustaining a diet lower in calories than your energy needs is thought to slow down your metabolism. This would make further weight loss nearly impossible. Enter reverse dieting!  Reverse dieting is a controlled process of slowly adding back calories to your diet after a period of caloric restriction. 

A typical reverse diet plan would add 50-100 calories/day for one week at a time, checking your body weight to achieve weight maintenance. Anecdotally, reverse dieting has been successfully used in the world of bodybuilding for years to promote the retention of muscle mass while keeping off body fat.

The Mechanisms Behind Reverse Dieting

In theory, weight loss should be easy- eat and move more. Unfortunately, obesity is somewhat of a self-sustaining state, because the condition of obesity creates a metabolic trap. High levels of body fat create an inflammatory state that disrupts one’s ability to break down fat stores. And obesity has been shown to affect appetite mechanisms in the brain, making one probe to overfeeding. Further complicating matters is the theory of metabolic adaptation - the notion that as you lose weight, your metabolism will shift to make further weight loss more challenging. Reverse dieting should counteract this effect.

To set up the theory: Metabolism can be viewed as an equation of energy balance. If your body weight is stable, you are in a state of energy balance, where energy intake (what you eat) = energy expenditure (the amount of energy you burn through resting metabolism, the cost of physical activity and the energy cost of digestion). To lose weight, you must enter a negative energy balance, where energy intake < energy expenditure.

According to the theory of metabolic adaptation, being in a state of negative energy balance lowers your resting metabolic rate. Your resting metabolic rate is mainly determined by the amount of body mass you have, particularly the fat-free mass. Therefore, as you lose body weight you will have to restrict calories further to continue losing body weight, because your resting energy needs diminish. 

Evidence Supporting Metabolic Adaptation

What evidence supports metabolic adaptation? To put it succinctly, studies measuring metabolic adaptation following weight loss tend to show the changes we would expect, but to a minor effect. One example study reported a 110-calorie per day reduction in resting metabolic rate immediately following a substantial 12kg (~25 lb) weight loss, which then was halved to about a 50 calorie reduction in resting energy expenditure following 4wks of weight stabilization – akin to a reverse diet period. 

On the flip side – overfeeding should produce an increase in energy expenditure, and it does, but it is small! Overfeeding subjects 40% more calories beyond their resting energy needs produced an increase in resting metabolic rate  - but it was only 23kcal/day – an inconsequential amount. So there are measurable changes in resting metabolic rate that correspond to the changes we would expect from the theory of metabolic adaptation – however, the changes we can measure are such a small amount as to seem irrelevant in practical terms.

Reverse Dieting and Long-Term Weight Maintenance

So where does this leave us? The good news is that there is no strong evidence supporting a drastic reduction in resting metabolic rate following a weight-loss diet. This is good news because it has been postulated that weight-cycling, or repeated weight loss attempts followed by weight regain could somehow “mess up” one’s metabolism. 

Happily, there is no evidence that weight cycling predicts long term health problems, such as an increased risk of type 2 diabetes. Further, changes in metabolism following weight loss have not been linked to the extent of regain. The negative health impacts of obesity are undisputed, and there is no good evidence to refrain from attempts at weight loss in fear of harming your metabolism.

Reverse dieting presents a good strategy towards achieving long-term weight maintenance. Failed attempts at weight loss often follow a strategy of being “on a diet” and then going back to one’s typical eating habits – a recipe for weight regain. A reverse diet, in which one implements a planned increase in caloric intake above deficit levels to achieve a stable energy balance, can help one avoid unconsciously reverting to previous overeating.

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