You've heard it before: Losing weight is about eating less and exercising more. But what if someone told you those two things aren't, ahem, weighted equally? In fact, they're not even close.

Dr. Yoni Freedhoff, medical director of the Bariatric Medical Institute in Ottawa and author of The Diet Fix (Random House, 2014), says that for every six pounds a person successfully loses, five pounds comes from diet and just one comes from exercise. "Giving fitness equal billing really detracts from the fact that it's the kitchen not the gym that's going to help with losing weight," says Dr. Freedhoff, who insists the real relationship between diet and exercise is not even close to 50-50. "If exercise were sufficient to lead to sustained and substantial weight loss, the problem of obesity wouldn't exist." Here are three things you need to know about exercise and weight loss.

1. Working out doesn't help you lose weight
Dr. Freedhoff says there are a number of reasons why exercise doesn't lead to weight loss the way we think it should. Much of that is due to the widely shared mentality that when you burn off calories, you've earned the right to eat extra later on. "So pushing people toward exercise with the hope of them losing actually has led some to gain weight, not lose weight," says Dr. Freedhoff.

Furthermore, he explains that those calorie trackers you use on the treadmill (the ones that lead you to believe you deserve an extra snack after your workout) often overestimate how much energy you've burned. For one thing, they attribute all speeds and activities to running (while many people walk on treadmills, which requires less energy), and for another, they don't discount the number of calories you would have burned anyways if you had been lounging around on the couch (since we burn some level of calories all the time for basic metabolic functions).

"It's why the gyms are full in January and empty by March," says Dr. Freedhoff. "People take on tons of exercise, then they don't change weight and they quit."

2. Less is more when it comes to working out
While some people love exercise, others see it as a necessary evil. And that's OK, says Dr. Freedhoff. But he recommends finding the exercise you like best (or despise the least) and determine the amount you can actually stick with. "I call it getting your toothbrush level of exercise," he says. "Just like you (hopefully) brush your teeth on a regular basis, what is the amount that you could actually exercise on a regular basis? Is it five minutes a day? Is it 10 minutes a day? What fits your lifestyle?"

According to Dr. Freedhoff, there is no ideal kind of exercise, so if you'd rather go for a walk than do a boot camp style class, go for it. "The exercise that is the best for weight management is the exercise you like enough to actually keep doing," he says. "It would be far more beneficial for a person to do 10 minutes a day of walking than to start going to the gym for 45 minutes three times a week then just quit."

3. Exercise can help you eat better
Though exercise isn't all it's cracked up to be in the weight loss department, there is one interesting benefit that Dr. Freedhoff observes in his patients: Those who exercise are more likely to eat better. That's because the exercise improves sleep, decreases pain, boosts moods—all things that can impact people's decision-making around their diets.

"Those lead people to make better dietary choices, to have more energy to cook and that sort of thing. It's not directly from the calories burned," he explains. "The indirect impact of exercise is real on behaviour. You feel good. It's easier to make the other changes you're trying to make."

So go ahead and get fit. It's good for you, and it will set you up for success in your weight-loss plan. But focus on your diet when you're putting that weight-loss plan into action, because, as Dr. Freedhoff says, "We can't outrun our forks."