The old diet adage “eat breakfast like a king, dinner like an indigent” might hold true, according to another review.

It’s generally thought that eating at night makes you fat, but is it true? Many individuals certainly think so, accusing their bulging bellies and thighs on their nighttime snacking. Reality may lie somewhere between an absolute yes and no — weight loss truly depends both on what you eat and when you eat it.

“Is a calorie only a calorie? That is debatable,” says Jim White, RD, owner of Jim White Nutrition & Fitness Studios in Virginia Beach, Va., and a representative for the Academy of Nutrition and Dietetics.

The thinking behind the possibility that eating at night can lead to weight gain goes like this:

You gain weight because the foods you eat at night are extra calories you probably don’t need. “The calories you consume after dinner are in excess of your everyday fare,” White explains. Extra calories equal extra weight. Another reason that calories from nighttime snacking are thought to be diet saboteurs, he says, is that the body does not consume calories as efficiently when you’re sleeping as it does during the day when you are active.

At night, body temperature drops and leptin (a hormone that smothers hunger) rises, generating a maelstrom perfect for weight gain if you do indulge in extra calories, White explains. “Increase that with not getting enough sleep and the effect that it has on metabolic hormones and you have a recipe for disaster,” he says.

A review of mice at Northwestern University supports the theory that nighttime snacking may lead to weight gain. Mice encouraged a high-fat diet during the day when they usually would sleep, gained significantly more weight than mice eating the same diet at night. The mice that ate when they should have slept saw their weight increase 48 percent from their baseline number, while the mice that ate at night saw their weight increase only 20 percent.

White trusts more research is required before anybody can say definitively that nighttime snacking is responsible for excessive weight gain. “Studies have just been conducted on mice, and the results can’t automatically be parlayed to people,” he cautions. However, he does offer up another reason not to eat nearer than 60 to 90 minutes before bed: You need to give your body time to digest. “Digestion takes vitality, and sleeping energy needs to be reserved for rest and recovery,” he clarifies.

Eating at Night: Diet Saboteur?

Marisa Moore, RD, LD, a food and nutrition consultant in Atlanta and also a spokeswoman for the Academy of Nutrition and Dietetics, doesn’t trust that eating at night in and of itself is a diet downfall.

“It’s what you are doing throughout the entire day that matters,” she says. “If you eat a larger number of calories than you burn in a day, you gain weight. If you eat fewer calories than you consume, you lose weight. Eat the same amount that your body needs in a day and you maintain your weight. It’s about that calorie adjust the entire day and not just at night.”

How Your Body Stores Fat

Whenever you eat, if your other energy sources (starches stored in the form of glycogen) are sufficient, your body will stow extra calories as fat. It will only call on stored energy when other sources of vitality run low.

Your body consumes calories whether you’re resting or exercising. Your cells, organs, and tissues require constant energy to function – it’s just that you consume calories at a slower rate when resting. You can rev up your resting digestion, though, by building more muscle: A pound of muscle consumes three times as many calories as a pound of fat. The more calories you burn, the easier it is to achieve your weight-loss goals.