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The American College of Sports Medicine recently published a consensus statement summarizing the latest research on physical activity and excess body weight. Exercise has long been recommended as part of treatment plan designed to lose unwanted pounds, but does science still support the notion exercise is an important component in weight loss?

Societal standards of what constitutes an ideal weight aside, most health-care professionals advocate weight loss based on its effect on health, not how you look in a pair of jeans. Carrying too much weight increases the risk of heart disease, high blood pressure, stroke, type 2 diabetes, some cancers and breathing problems.

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Yet the difficulty in prescribing exercise as a weight-loss tool is not only does it take a lot of exercise to affect weight, but individuals carrying excess pounds are less likely to start an exercise program and if they do, they are also more likely to drop out.

Another issue is weight-loss success from exercise alone isn’t guaranteed, even if the same group of people follow the same exercise routine. And while there’s some evidence suggesting it takes a minimum of 150 minutes per week of moderate to vigorous intensity exercise to move the numbers on the scale, there’s no consensus among experts it’s enough, especially given the variability of the results in study subjects.

Even then weight loss is modest if there’s no concurrent reduction in the daily number of calories consumed. According to the ACSM, one can expect a modest weight loss of only 0.5-3 kg when using exercise as the sole strategy to lose weight. It’s only when diet and exercise are combined the results become more significant.  

“When combined with an energy-restricted diet, the effect of physical activity on body weight and adiposity is additive to diet and enhances weight loss by approximately 20 per cent, compared to what is observed with an energy-restricted diet alone,” said the authors of the ACSM’s latest consensus statement.

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As to what kind of exercise is most effective at losing unwanted weight, there is little evidence suggesting one form of physical activity is better than the other. But if you want the most bang for your buck in the gym, it’s clear intensity matters. Moderate to vigorous intensity workouts will burn calories at a greater rate than light intensity activities, so keep that in mind if finding time to exercise is an issue.

The same goes for diet. There’s no evidence suggesting one diet is more effective than the other when it comes to creating a successful weight-loss routine, including time-restricted eating and intermittent fasting. The most important thing is to consume fewer calories, how you do it seems to make little difference in the long run.

“At the population level, one type of diet and macronutrient composition does not appear to be more effective for weight loss when compared to other approaches, provided these approaches result in similar effects in achieving negative energy balance,” stated the ASCM in its consensus statement.

In addition to clearing up any confusion as to whether one diet and exercise combination is more effective than another, the ACSM also addressed the idea eating at a certain time of day may be more advantageous for weight loss. Based on the theory exercise blunts appetite and eating fewer calories in the morning results in a greater negative energy balance than eating fewer calories at night, there’s little evidence restricting eating and exercise to certain times of day is an effective weight-loss strategy.

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Also, worthy of mention by the ACSM is except for intense exercise (greater than 70 per cent of maximum effort), physical activity has little effect on appetite. Any suppression of hunger post-exercise is short-lived and doesn’t have an effect on the number of calories consumed daily, so don’t count on exercise to make that trip to the cookie jar seem less appealing.  

What does aid diet and exercise in whittling down body weight is the use of smart watches/wearables and apps. Not surprisingly, the ability to set daily activity and energy expenditure goals, track physical activity and diet and get real time feedback on lifestyle habits as well as reminders to get moving has proved to enhance weight loss.

“In 73 per cent of instances, greater monitoring of physical activity behaviour was linked to greater weight losses,” stated the ACSM consensus statement. “This suggests that for those with overweight and obesity, the self-regulatory process of monitoring raises awareness of physical activity and diet behaviour and enables a feedback loop of gathering and receiving personal data to make progress toward weight-related goals.”

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This latest update on the role of exercise in weight loss hasn’t shaken the ACSM’s belief it’s still a valuable weight-loss tool, including for those taking anti-obesity medications. Diet and exercise still move the numbers on the scale. It’s also a reminder the benefits of exercise go beyond cinching your belt a little tighter. Improved health, vitality, sleep and mood and more muscle mass are just some of the advantages of regular exercise, even for those who struggle to reach their weight-loss goals. It takes as little as a five per cent decrease in body weight to start accruing health benefits, so every workout offers a reward — even if it can’t be seen.

“ACSM advocates for physical activity to be a key element of prevention and treatment efforts for exercise body weight and adiposity, with a focus on implementation of inclusive approaches to facilitate adoption and sustained engagement of physical activity of all persons,” stated the ACSM in their consensus statement.

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