Why you shouldn’t exercise to lose weight, explained with 60+ studies
Welcome to Show Me the Evidence , where we go beyond the frenzy of daily headlines to take a deeper look at the state of science surrounding the most pressing health questions of the day.
“I’m going to make you work hard,” a blonde and perfectly muscled fitness instructor screamed at me in a recent spinning class, “so you can have that second drink at happy hour!”
The spinning instructor was echoing a message we’ve been getting for years: As long as you get on that bike or treadmill, you can keep indulging — and still lose weight. It’s been reinforced by fitness gurus, celebrities, food and beverage companies like PepsiCo and Coca-Cola, and even public-health officials, doctors, and the first lady of the United States. Countless gym memberships, fitness tracking devices, sports drinks, and workout videos have been sold on this promise. . .
There’s just one problem: This message is not only wrong, it’s leading us astray in our fight against obesity.
Despite the prevailing advice, exercise is pretty unhelpful for weight loss. While 100 percent of the energy we gain comes from food, we can only burn off about 10-30 percent of it from physical activity each day.
Exercise alone does NOT lead to weight loss. 
An Olympic runner cannot burn off the calories of the slowest eater.
Medical Myths originate when someone benefits from misleading advice.
Medical Myths disappear when Patients pay attention to scientific advice.