Exercise may or may not provide help to reduce weight and keep it off – here’s the evidence for either side of the debate

The global fitness industry will generate over US$80 billion in revenue in 2023, estimates suggest. And why not, given the various excellent reasons to exercise? Better cardiovascular health, lower risk of Type 2 diabetes, stronger immune system – the list goes on.

One of the most important reasons many individuals decide to exercise is to reduce weight. As a biobehavioral scientistI study links between behavior and health, and I heed the time-honored advice that eating less and exercising more are mandatory to reduce weight. But a recent debate within the scientific community highlights the growing suspicion that the “exercising more” a part of this recommendation could also be erroneous.

At the middle of the talk is the constrained total energy expenditure hypothesiswhich asserts that exercise won’t provide help to burn more calories overall because your body will compensate by burning fewer calories after your workout. Thus, exercise won’t provide help to reduce weight even when it’ll profit your health in countless other ways.

Obesity researchers take issue with this hypothesis, since it’s based on observational research moderately than randomized controlled trials, or RCTs, the gold standard of scientific evidence. In RCTs, participants are randomly assigned to either a treatment or a control group, which allows researchers to find out whether the treatment causes an effect. Randomized controlled trials have shown that exercise causes weight reduction.

The verdict is definitely more mixed when considering all of the gold-standard evidence available.

What the evidence says

Spectators of this hypothesis have emphasized the importance of systematically reviewing the evidence from all gold-standard trials. They pointed to a 2021 review of greater than 100 exercise studies that examined the effect on weight reduction in adults of aerobic, resistance or high-intensity interval training together or alone. The review concluded that supervised exercise regimens do cause weight reductioneven when only a modest amount.

So that settles the talk, yes? If you eat an excessive amount of dessert, then you definitely can just go on an additional run to burn off those extra calories, right?

Well, not exactly.

If extra physical exercise burns extra calories overall, then exercise must also keep the load from coming back after low-calorie weight-reduction plan. But keeping those lost kilos off after weight-reduction plan is a typical challenge. The same 2021 review includes the few randomized controlled trials that address the query of whether exercise facilitates weight maintenance. However, the outcomes weren’t pretty much as good as they were for weight reduction. The researchers found that six to 12 months of aerobic exercise, resistance training or each after weight-reduction plan didn’t prevent weight regain in adults.

Exercise adherence

But what about compliance? Did all of the people in those studies actually exercise repeatedly?

The 2021 review found just one randomized controlled trial on weight maintenance that reported an objective compliance ratemeaning each exercise session was supervised by a trainer. This tells us the share of time that participants within the study actually exercised as prescribed.

In that trial, the compliance rate was only 64% for 25 post-menopausal women who accomplished a resistance training program after diet-induced weight reduction. This was for a regimen through which participants needed to are available in and exercise two to thrice per week for a whole 12 months. From the attitude of maintaining with a program for that long, doing so 64% of the time doesn’t seem so bad.

But they still gained back as much weight because the 29 women within the control group who weren’t enrolled within the exercise program.

Energy balance

Many people would say that it’s all about balancing energy in from food and energy out from exercise. If exercise didn’t keep the load off, then perhaps a much bigger dose of exercise was needed.

The American College of Sports Medicine highlighted this issue of exercise dose in its 2009 position statement on physical activity for weight maintenance, stating that the quantity of physical activity needed for weight maintenance after weight reduction is uncertain. Moreover, it stated that there’s a lack of randomized controlled trials on this area that use state-of-the-art techniques to watch the energy balance of participants.

Fortunately, among the authors of the position statement went on to make use of state-of-the-art techniques to watch energy balance in their very own randomized controlled trial. In 2015, they enrolled chubby adults right into a 10-month aerobic exercise program and compared the energy intake of those that lost weight with the energy intake of those that didn’t reduce weight while on this system. They found that those that didn’t reduce weight were indeed taking in additional calories.

Mystery of the disappearing calories

But there’s something else in that 2015 study’s energy measurements that is kind of interesting. By the tip of the study, the variety of total day by day calories the exercisers burned was not significantly different from what the nonexercisers burned. And this was regardless of the proven fact that trainers verified the exercisers burned an additional 400 to 600 calories per session at their nearly day by day exercise sessions. Why didn’t those extra exercise calories show up in the whole day by day calories burned?

The answer to that query may help explain why exercise doesn’t at all times provide help to keep the load off: Your metabolism responds to regular exercise by decreasing the variety of calories you burn if you’re not exercising. That’s in keeping with the constrained total energy expenditure hypothesis that spurred the present debate.

Researchers recently tested the hypothesis by measuring the nonexercise calorie burn of 29 obese adults over an almost 24-hour period, each before and after a six-month exercise program. They found that the calories they burned once they weren’t understanding did decrease after months of normal exercise – but only in those that were prescribed the upper of two different exercise doses.

Those who exercised on the lower dose for general health, meaning they burned an additional 800 to 1,000 calories per week, saw no change of their metabolic rate. But those that exercised at the upper dose to reduce weight or maintain weight reduction, meaning they burned an additional 2,000 to 2,500 calories per week, had a decrease of their metabolic rate by the study’s end.

Exercise for health

Perhaps either side of the talk are right. If you need to lose a modest amount of weight, then a brand new exercise routine might make a modest contribution toward meeting that goal.

However, as others have said, don’t idiot yourself into considering you possibly can “outrun a nasty weight loss program” by simply exercising more. There is a diminishing marginal return to exercise – you finally take less weight off for the extra exercise you place in.

But even when extra exercise may not provide help to reduce weight and keep it off, there are still the opposite great health dividends that regular exercise pays out.