A recent study in the British Journal of Sports Medicine made several great points about the complete futility of trying to lose weight with exercise alone, or use exercise to compensate for a diet full of processed foods and sugar-loaded sodas:
- It’s trivially easy to eat many more calories from processed foods than you can reasonably burn, even if you’re very active and work out every day. For example, to burn off all 1,000+ calories in 1 slice of The Cheesecake Factory’s Godiva Chocolate Cheesecake (is your mouth watering yet?), a 120-pound woman would have to jog for about 3 and a half hours – and that’s just dessert!
- The food industry has a vested interest in making you believe that you can easily out-exercise a junk diet, because it gives them license to keep selling you junk food. But just because it’s profitable for the food industry to say doesn’t make it true.
- Besides, even if you were dedicated enough to burn off a bunch of extra junk food calories every day, is that really how you want to spend your life? Hour after hour of running so you can “afford” your sugar hit? Does anyone have time for that?
- Childhood obesity is not caused by physical inactivity, and interventions to increase physical activity are not effective. Children (and adolescents) are getting fatter because they’re eating more, not because they’re moving less.
All of this evidence is often used to support the conclusion that exercise is useless for weight loss. It’s great for health and overall well-being – everyone is rightly very quick to point that out – but not all things that make you healthier do so by reducing your weight. Weight loss and health are two very different things, and trying to conflate them only leads to the useless and painful “cardio-to-earn-dessert” model of exercise.
But hold on just a minute. Just because exercise doesn’t magically produce weight loss on a diet of pizza and beer doesn’t mean it’s not useful. Exercise does help with weight loss – it just isn’t sufficient all by itself, and it doesn’t work through calorie burning. If you’re using a daily jog to “earn dessert,” then you’re unlikely to see great results. If you’re using a daily jog to “earn” a cinnamon roll for breakfast, a Frappuccino at 10, pizza for lunch, a chocolate bar at 3pm, and a slice of cheesecake after dinner, then you’re really in trouble. But on the other hand, if you’re using exercise intelligently in addition to a solid diet, then it can be a great tool to help restore metabolic health and give you psychological motivation to keep going.
Benefits of Exercise: Hormones
First of all, the idea that “exercise doesn’t help with weight loss because it doesn’t burn tons of calories” is silly, because weight loss isn’t just about eating as little as possible and burning as many calories as you can. It’s also about the hormonal environment in your body, and whether your body is set up metabolically to store fat or to burn it.
One of the big drivers of that is the hormone insulin (here’s a primer on insulin if you need one). The authors of the study above slammed excess carbs as the cause of insulin problems, directly leading to obesity – that’s one factor, but it’s very simplistic. For one thing, in healthy people, a moderate intake of dietary carbs doesn’t actually compromise insulin function, and doesn’t cause metabolic problems or obesity. And in people who do have problems with insulin (e.g. people with diabetes), there are answers other than an extremely low-carb diet. Exercise is one of the best ways to restore insulin sensitivity, and better insulin sensitivity means benefits like…
- Fewer blood sugar highs and crashes.
- Greater ability to burn calories for energy instead of storing them as fat.
- Better regulation of appetite-controlling hormones, like leptin.
None of these things will spontaneously cause weight loss if you’re also eating a massive calorie surplus, but they’re all very helpful if your diet is reasonably dialed in. Who wouldn’t want sustained energy without getting massive carb cravings every few hours? How could that possibly not help you lose weight?
Benefits of Exercise: Mental and Social Benefits
Then there’s the mental health side of things. Exercise just makes most people feel good – it gives you more energy, it’s moderately effective for treating depression, and it’s an effective stress management tool. It's one of the best tools around for improving mental health in general.
Okay, so you feel great, but how does this help you lose weight? Because having more energy makes it easier to maintain healthy behaviors even when they’re not totally convenient.
When are you more likely to turn to a plate of brownies for comfort: when you’re stressed to the limit, or when you’re energetic and feeling great? When are you more likely to give up on healthy home cooking and just order takeout, when you’re so tired you can barely keep your eyes open, or when you have plenty of pep to spare? More energy overall means more energy to spare for making healthy choices even when it takes effort (and let’s be honest, often it does!)
Studies have also shown that exercise actually reduces sugar cravings. For example, in this study, the researchers found that a 15-minute walk was enough to reduce their subjects’ desire for a chocolate snack. The exercise also helped reduce the power of stress to induce cravings. Technically, there’s no calorie difference between “not craving chocolate” and “craving chocolate but white-knuckling it,” but in the real world where people frequently do cave to their cravings, reducing them is a very major benefit.
Another benefit of exercise is harder to pin down or measure, but it’s just as real: the cultural and social pros of being around other people who care about their health. Just being part of a gym community, running club, or other athletic group can help you stay motivated to eat well (so your workouts will keep feeling awesome). Gym buddies are a great source of healthy recipe suggestions and overall companionship, which makes a healthy lifestyle in general more pleasant to live.
Summing it Up
Exercise is extremely good for your health, but it’s not an activity that makes you lose weight by letting you eat whatever you want because your half-hour jog burns off thousands of calories of junk food every day. In that sense no, exercise “doesn’t work” for weight loss.
But if you deploy exercise strategically in addition to a healthy diet, then it absolutely can give you a leg up with your weight-loss efforts – not because it burns a lot of calories, but because it re-regulates carbohydrate metabolism, improves mood, and helps reduce cravings. It’s not necessary, but it’s helpful. Even something as gentle as walking can help improve insulin sensitivity and get you out of the house for a little sunshine now and again: it doesn’t have to be extreme.
It also doesn't have to be cardio: once you free yourself of the compulsion to burn calories through exercise, you can explore strength training, sprinting, and other kinds of exercise that don't burn as many calories but have amazing benefits for bone and muscle health, overall fitness, and other parts of your life. Exercise is just so much better when you let go of maximizing "calories out" - and thanks to the ways it actually does work for weight loss, it'll still help you reach your goals.
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