Experts Weigh In on How Much Exercise Affects Weight Loss and Weight Maintenance
Reviewed by Louise Chang, MD
You've heard it time and again -- to lose weight, you need to exercise and watch your diet, so that your calories burned exceed your calories consumed.
But if you've been working out and your extra pounds won't budge, you may be wondering why that seemingly simple strategy isn't working.
Don't hang up your sneakers and throw in the towel. If you do, you're going to miss out on the biggest weight perk exercise has to offer, experts tell WebMD.
First, you may need a reality check about what to expect from exercise. Here are five truths about exercise and your weight.
1. Exercise is only part of the weight loss story.
On the couch or in the gym, there's no getting around your tab of calories in and calories out.
Robert Kushner, MD, is a professor of medicine at Northwestern University and clinical director of the Northwestern Comprehensive Center on Obesity. He says the obese patients he treats often tell him they're not seeing the results they want from exercise.
"They typically will say, 'I have been working out three days a week for 30 minutes for the past three months and I have lost 2 pounds; there's something wrong with my metabolism,'" Kushner tells WebMD.
Kushner says he tells patients that exercise is very good for them, but for weight loss, he emphasizes a healthy diet in the beginning.
"First, we've got to get a handle on your diet," Kushner says. "Then, as you're losing weight and feel better and you're lighter on your feet, then we shift more and more toward being more physically active; and then living a physically active lifestyle for the rest of your life is going to be important to keeping your weight off."
Kushner's strategy is "certainly one reasonable approach," but others have had success including physical activity early on, says James O. Hill, PhD, professor of pediatrics and medicine and the director of the Center for Human Nutrition at the University of Colorado at Denver.
It's easier to cut 1,000 calories from a bloated diet than to burn off 1,000 calories through exercise, Hill notes. "But there are many, many studies that show that exercise is associated with weight loss when done in enough volume and consistently," Hill says. "It depends how much you do."
Pamela Peeke, MD, MPH, FACP, says she emphasizes physical activity right away with obese patients, partly for its mind-body benefits.
"Fitness is my middle name," says Peeke, who is the spokeswoman for the American College of Sports Medicine's "Exercise is Medicine" campaign. "I immediately add physical activity, but I do it gently."
Peeke says she asks her patients to start walking as a way to "celebrate" their body with activity. "For years, they've blown off their body," Peeke says. "By having them actually use their body ... they can begin to integrate their body back into their life and not use it as a source of torture or torment or shame." Peeke shares more of her views on exercise and weight loss in herWebMD blog.
2. Exercise is a must for weight maintenance.
All of the experts interviewed for this story stress this fact: No matter how you lose extra pounds, you're going to need to be active to keep them off.
"I come back to this over and over and over -- you can't find very many people maintaining a healthy weight who aren't regular exercisers," Hill says.
"What we find is that people that focus on diet aren't very successful in the long run without also focusing on physical activity," Hill says. He warns that people can be "wildly successful temporarily" at losing weight through diet alone, but there's plenty of data that show that those people regain the weight if they aren't physically active.
"When it comes to weight, you can't talk about diet alone and you can't talk about exercise alone ... you absolutely have to address both issues at the same time," says Timothy Church, MD, MPH, PhD, director of preventive medicine research at the Pennington Biomedical Research Center in Baton Rouge, La.
3. Food splurges may undo your efforts.
Exercise may not buy you as much calorie wiggle room as you think.
"The average person overestimates the amount of activity they're doing by about 30% and underestimates their food intake by about 30%," says Kathianne Sellers Williams, MEd, RD, LD, a registered dietitian, personal trainer, and wellness coach in Atlanta.
Williams has seen that with her clients. "When' I'm looking at people's food and activity logs, sometimes things just don't add up," she says. "I do think that people think, 'Oh, I just did 60 minutes at the gym' or 'I just did 30 minutes at the gym' and think that counteracts a lot of what they're eating. But the reality is, our food portions are huge."
Plus, you have to look at all the other calories you ate or drank that day, and how sedentary you were apart from your workout, Peeke says.
"The rest of the day, you're sitting down and you're also eating other things," Peeke says. "How are you going to burn that stuff, let alone this extra little treat that you just thought you wanted?"
It's hard to accurately estimate how many calories you burn working out, Church says.
"If it is a hard workout, you kind of intuitively think, 'Wow! That's cool! I just put enough in the bank for two days!' and you really haven't," Church says.
For instance, WebMD's Fit-O-Meter estimates that a 150-pound person who bikes fast for 30 minutes burns 341 calories. Let's say they would have burned 70 calories sitting on the couch watching TV; the extra calories they burned by biking drops down to 271 calories. That's less than the 300 calories in one tall caramel frappuccino, according to Starbucks' nutritional information.
And if you belly up to certain restaurant entrees recently singled out for sky-high calories by the nonprofit Center for Science in the Public Interest, you're going to have to bike a long, long time to zero out those calories.
4. Exercise machines may not tell the whole calorie story.
Treadmills and other exercise gear often have monitors that estimate how many calories you're burning.
Those displays are "close, but for each individual they can vary quite a bit," says Kong Chen, PhD, director of the metabolic research core at the National Institutes of Health.
Chen suggests using calorie displays on exercise equipment for motivation, but not to offset your eating.
"For example, it doesn't matter what it says, 300 or 400 calories. If you do that every day or increase on that level, then you've achieved your purpose. But if you're feeding yourself against that -- no, I wouldn't recommend that," Chen says.
Those machines may not subtract the calories you would burn without exercising.
"It isn't 220 calories for those 40 minutes [of exercise] versus zero. If they were sitting at work or playing with their kids, they're probably burning 70 calories during that period of time," Kushner says. "You have to subtract out what you would burn if you didn't exercise. So it really becomes much less."
5. One daily workout may not be enough.
Your best bet for your weight -- and for your overall health -- is to lead a physically active lifestyle that goes above and beyond a brief bout of exercise.
"It's not just about 30 minutes of exercise," Chen says. "It's about fighting the sedentary environment."
"The message isn't that the 30 minutes on the treadmill isn't good; it's that the 30 minutes on the treadmill isn't going to make up for 23-and-a-half sedentary hours," Hill says. He encourages people to weave activity throughout the day. "Do something to move and make it fun," he says.
Chen also recommends setting realistic expectations and taking "small steps all the time" toward your weight goal.
As much as calories in, calories out matters, don't forget about stress, sleep, and other factors that can affect your weight, Williams says.
"We need to look at someone's total lifestyle, not just whether someone hits the gym," she says. "Weight and obesity are really multifactorial, and it really simplifies it just to break down to nutrition and exercise. Those are really big pieces, but definitely not the only pieces."