Long ago I had one of those "choose-your-own adventure" books based on a James Bond movie, and I made bad choices; the poor British spy kept getting consumed in a vat of molten lava, impaled on a bunch of spiky things or became an appetizer for saltwater crocodiles.

But when it comes to the exercise-then-choose-your-food adventure that that I’ve lived my whole life, however, I have a far better track record.

Do you know the three mealtime words that can cripple weight loss? "Because I exercised," said Dr. Yoni Freedhoff, an obesity researcher in Ottawa, Ontario.

Burning off 300 calories on an elliptical trainer then rewarding your efforts with a 500-calorie piece of cheesecake is just bad math. That’s the choice that leads to spiky, overweight crocodiles in lava. The other choice is realizing that burning calories is the least important thing exercise does. This choice takes advantage of the cognitive-boosting effects of physical activity to resist food rewards and make healthier choices that fuel performance.

Obesity researcher Dr. Sue Pedersen, a specialist in endocrinology and metabolism in Calgary, Alberta, explained, "The bottom line is that weight loss is 90 percent about diet."

You cannot out-exercise a bad diet. So go ahead, choose your own adventure.

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Adventure 1: "I exercise, so I earned this treat."

So we’re a few months into this New Year, and you’ve resolved to get in shape and lose weight. You’re going to the gym — walking, jogging, swimming, cycling or whatever. After a good workout, you think, "I’m exercising now. I deserve this treat."

This adventure is called the "reward mentality."

Because you exercised, as Freedhoff explained, you believe you have leeway in terms of dietary choices. You can have seconds, drink extra booze, care less about what you consume.

The problem, professor Eric Ravussin, of the Pennington Biomedical Research Center in Louisiana, explained to me, is that most obese people are incapable — both physiologically and psychologically — of the type of activity required to burn the calories required to achieve significant weight loss. They tend to overestimate just how many calories they burn via exercise then overcompensate with food reward.

It’s bad math, but it happens all the time. The downside to choosing this adventure is numerous studies showing exercise alone doesn’t lead to weight loss.

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Adventure 2: "I exercise, so I need healthy fuel."

Because weight loss is simple caloric restriction, it can be done easily by eating less, but in an environment with 24/7 McDonald’s, rapid pizza delivery and doughnuts at meetings, it’s hard to resist the constant call of the cookie, cream puff or cheeseburger.

"Exercise is a critical component of weight loss and weight maintenance," Dr. Miguel Alonso-Alonso, a Harvard neurologist and specialist in how exercise affects the brain, told me. "We know that. It’s a fact."

First off, stress eating is common, but exercise is one of the most powerful tools available for reducing stress. Beyond that, Alonso-Alonso says, it boosts your ability to stick to a plan. "Physical activity and eating behavior are connected in the brain at the cognitive level. It’s the same mental processes."

Alonso-Alonso explained we use goal-oriented systems in our brains to suppress those immediate impulses to eat junk food. "The resources for goal-oriented eating behavior are greatly enhanced via physical activity," he said. "Exercise improves eating behavior through brain and cognitive changes."

Healthy eating involves sticking to a plan. Exercise makes you better at sticking to a plan by enhancing "executive function" and decision-making ability. Every time you eat, good decisions plus higher executive function equals better decisions. Oh, and according to Brian Wansink, a professor of consumer behavior and nutritional sciences at Cornell University, we make more than 200 decisions about food every day.

"There is a dose-response effect," Alonso-Alonso said. "A fitter person is going to have greater improvements in executive function and therefore better control of what they eat."

Exercise also has the ability to help at the subconscious level. Although you may feel like you’re inhaling fire ants after a hard run, the reality is that physical activity has a rewarding effect on your brain. It elicits the same reward sensation as things like drugs, alcohol, gambling, and even junk food. A 2012 study of 30 people by researchers at California Polytechnic State University determined that exercise suppresses desire to eat by giving your brain an alternate, healthier fix.

But when it comes to appetite, not all exercises are created equal.

Another study from last year, this one by researchers at the University of Western Australia, used 33 sedentary people and found that those in the aerobic training group had increased satiety, but those in the resistance training group (such as weightlifting), did not.

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"Exercise is good to control appetite," says Nicole Avena, a research neuroscientist in the fields of diet and addiction at the University of Florida College of Medicine. "It releases hormones that are associated with satiety. You have a reduced desire to eat."

And you can take advantage of the sweet, sweaty memories of exercise too. "When you exercise it creates a life perspective where you don’t want to undo it all with an unhealthy diet," eating behaviorist Eric Stice of the Oregon Research Institute said.

Yale University obesity researcher Dr. David Katz told me that when it comes to better eating, exercise is "the wind beneath your wings."

"It helps you want to care more about yourself and make better food choices," he told me. "You want to put better fuel in the tank."

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Despite all the benefits of exercise for making better eating choices, many people still mess this up. They allow the reward mentality to override.

If weight loss is your goal, choose the right adventure and turn Freedhoff’s caution on its head. Say to yourself: "I can make most of my food choices good ones. I can resist eating junk food. I can do this. Because I exercised."