Do You Need to Exercise to Lose Weight?

Not everyone enjoys a sweat session, but exercise has long been touted as a key component of losing weight. Exactly how big a role it can play is still something of an open question, but a new analysis of the contestants who had lost a significant amount of body weight while on “The Biggest Loser” reality television show suggests that it can be an integral piece of the puzzle.

The analysis, published in the August 2021 edition of the research journal Obesity, reinterpreted data collected from contestants of the show. In a previous study, the author, Kevin D. Hall, noted that contestants experienced a dramatic slowing of their metabolisms after losing a lot of weight. He also noted that regaining the lost weight doesn’t restore the metabolism to its previous level, which helps explain why it’s so difficult to keep weight off after losing it.

In the new study, Hall attempts to explain those findings in more depth, using what he calls the “constrained model of human energy expenditure.” That model states that the body aims to keep an even keel in terms of energy expenditure and will turn down its metabolic rate when weight loss occurs.

From an evolutionary standpoint, this is great news – our hunter-gatherer ancestors could rely on the body’s precise energy-balance-keeping mechanism to help them get through lean times. But in the modern age, where far too many calories are on constant offer, that survival mechanism may be contributing to rising rates of obesity.

It’s a dynamic and complicated picture, but “the analysis appears to support the importance of continual physical activity for long-term weight loss and maintenance,” says Lisa Cooper, a registered dietitian with the Orlando Health Center for Health Improvement.

In other words, if you lose weight, you’ll need to maintain an exercise routine long term to keep it off. The analysis notes that “the contestants who sustained the greatest increases in physical activity expenditure at six years also maintained the greatest weight losses,” which suggests that an ongoing exercise regimen can help you keep off the weight you lose.

This is consistent with findings from a range of other studies, says Shaun Carrillo, lead wellness coach with Providence St. Joseph Hospital in Orange County, California. “There are countless studies supporting the value of exercising during weight loss.”

For example, one 2018 study, showed that “70% of people who lost weight and kept it off engaged in regular exercise programs. Of the people who didn’t keep it off, less than 30% engaged in regular exercise programs.”

It stands to reason that exercise will help you shed excess weight and keep it off because “exercise is a great way to create a calorie deficit, meaning burning more calories than you’re consuming,” says Andrea Whitson, a clinical dietitian with Santa Clara Valley Medical Center in San Jose, California, and a certified aerobics instructor with Athletics and Fitness Association of America.

“The body has to burn 3,500 calories to lose 1 pound of weight,” Whitson says. “This can either be done by decreasing intake, increasing exercise or a combination of both.”

While it’s entirely possible to create the needed calorie deficit to lose weight through dietary changes alone – such as adopting a low-calorie diet – “the combination of diet and exercise is important because of the role physical activity plays in energy balance, helping with weight loss and keeping extra weight off once it has been lost,” Cooper says.

Carrillo says that adding exercise to dieting is a more effective approach because dieting alone means you’ll lose fat and lean mass, or muscle. And that’s a problem because “lean mass plays a vital role in weight loss because the more lean mass you have, the more calories you burn.”

What’s more, “physical activity helps reduce abdominal fat and preserves muscle during weight loss,” Cooper says. “Dieting without exercise may result in loss of some lean muscle mass, along with fat. Exercise helps to protect, or even build lean muscle mass, which is critical to maintaining metabolism.”

It’s all about balance, Carrillo says. “People often set themselves up for failure by trying to follow strict or ‘magic pill’ diets.” The better approach is to strike “a healthy balance between eating well and exercising, while still occasionally indulging.” This makes for “a more sustainable weight loss journey.”

Exactly how much exercise you’ll need to lose weight varies from person to person, Cooper says. “Many may need more than 150 minutes a week of moderate-intensity aerobic physical activity to lose weight or keep it off.”

Carillon notes that the American College of Sports Medicine recommends more than 250 minutes of moderate-intensity physical activity per week to lose weight and prevent regaining it. “You should try to burn 300 to 400 calories per workout session and exercise for a minimum of 3 days per week, but preferably daily.”

The Physical Activity Guidelines for Americans, 2nd edition notes that both people who want to lose a substantial amount of weight, meaning more than 5% of their body weight, and those who are trying to keep a significant amount of weight off once it has been lost, may need to do more than 300 minutes of moderate-intensity activity per week to meet weight-control goals, Cooper says.

It all comes back to creating a sustainable calorie deficit, Whitson says. “To lose 1 pound per week, you would need to decrease your calorie intake by 500 per day if you’re not exercising.”

Cutting your caloric intake by 500 calories per day could leave you feeling hungry, but if you create that deficit through a combination of exercise and diet – 250 calories burned and 250 calories cut from the daily intake – that’s “more realistic,” and may keep you on track.

Exactly which exercises work fastest is also up for debate, but Carrillo notes that high intensity interval training, or HIIT, “is one of the most efficient ways to burn calories. HIIT is effective because it combines short intervals of high intensity exercise with minimal rest. Several studies have shown that HIIT workouts can increase your metabolic rate for hours after exercising, meaning that you’re burning calories hours after your workout is over.”

Ultimately, whichever type of exercise you like can do the trick, Carrillo says. “Exercise is not a one-size-fits-all. Whether it’s walking, swimming, yoga or boot camps, choose something that you enjoy and do it consistently. The most important factor when it comes to weight loss is sustainability.”

In addition to helping create the caloric deficit needed to lose weight, exercise is also great for building and maintaining muscle mass, “which will help your body burn more calories throughout the day,” Whitson says. Other benefits of exercise include:

To create more muscle, Whitson says incorporating more resistance training is key. Examples include:

If you’re trying to lose weight, staying consistent with your diet and exercise program is critical. And it will take some planning ahead to stay on track, Whitson says.

“It may be something like keeping a bag with your training shoes and athletic clothing in your car. You can then be ready to take a walk or a run whenever is good for you. Or having your athletic clothes and shoes ready and laid out for when you wake up in the morning.”

She also recommends setting small goals and rewarding yourself when you meet them. But she cautions the reward should be something other than food. Opt instead for “something you enjoy like new athletic clothes or going to a movie.”

Small bits of exercise throughout the day can add up. For example, 10 minutes on your lunch break, 10 minutes after work and another 10 minutes after dinner is as good as 30 minutes all at once, Whitson says.

Carrillo agrees, adding that “exercise doesn’t have to be intimidating. Start small: Walk for 30 minutes a day, then slowly build up to resistance and interval training.”

But getting consistent with it while keeping control of your diet will lead to better results.

“Physical activity and good nutrition go hand-in-hand for promoting healthy weight loss,” Cooper says. “Consult a registered dietitian and certified fitness trainer for specific individualized nutrition recommendations and exercise plans.”