When losing fat, rapid drops in body weight seems appealing but was always thought to come with trade offs. A new meta-analysis compared the effects of rapid versus slow weight loss on resting metabolic rate and a variety of body composition outcomes. 

People love fast results. Just scan the health and wellness market and you’ll see tons of programs, supplements, and other products that promise the world with little effort and time required.

IF you’re reading this article however, you most certainly know that most of those products are complete garbage.

When we start to diet and introduce a caloric deficit, our bodies have the capacity to respond with a number of adaptations that serve to increase hunger and reduce energy expenditure.

In addition, the body must coordinate a fine balance of anabolic (building) and catabolic (breaking down) processes, ultimately influencing how much lean mass we’re able to retain.

It has been hypothesized that slower rates of weight loss, which require a smaller daily energy deficit, might attenuate drops in energy expenditure and lean mass when compared to faster rates of weight loss.

But slow and steady also means a prolonged diet process which can have it’s own consequences…


The purpose of the presently reviewed meta-analysis was to determine if the rate of weight loss meaningfully impacts changes in resting metabolic rate or a number of body composition outcomes.

For meta-analyses, the results of several previous studies are combined, so all of the participants are pooled together into one big group.

For the seven studies that met inclusion criteria for this meta-analysis, there were 167 subjects that received a slower weight loss intervention and 194 subjects that received a faster weight loss intervention.

All of the included studies recruited subjects between the ages of 18 and 70 years old, who had BMI values classified as overweight or obese.


Total weight loss was very similar for slow and fast weight loss groups

However, Slower weight loss led to slightly greater reductions in FAT mass, and slightly smaller reductions in fat-free mass and resting metabolic rate. AKA a higher percentage of fat was lost and more muscle was retained.

Resting metabolic rate generally dropped a little bit in both groups, but the drop was about 57.5kcal/day larger in the fast groups than the slow groups.

Key Takeaways

  1. The research indicates that slower rates of weight loss are probably as good as or better than faster rates if we’re concerned about retaining as much muscle as possible, minimizing performance reductions during weight loss, and minimizing the drop in resting energy expenditure that occurs during the active weight loss period
  2. There are some potential advantages of faster rates of weight loss. The most obvious one, of course, is that it’s the quickest path to the end goal. It’s important to keep in mind that progress can fuel motivation. Slow rates of weight loss might be more sustainable on paper, but it unavoidably ensures that progress will be slower which can cause individuals to lose enthusiasm.