Calories in versus calories out. That’s all weight loss (or weight gain) really is.
Burn more calories than you take in every day, and you’ll drop pounds. Eat more calories than you use, and your weight will go up. If only weight loss was actually that simple.
“Nutritionists often say ‘a calorie is a calorie,’ and while this is technically true, there may be more to the story than just how many calories you consume,” says Carolyn Alish, Ph.D., R.D., a nutritional researcher at Abbott Laboratories.
After all, while you’ll lose weight in the short term by eating 1,500 calories a day from junk food (granted you’re burning more than that), when you get all of your calories from refined, sugar-filled foods, you set your blood sugar up on a crash course that ends in a trifecta of fat accumulation, insulin resistance, and Type 2 diabetes. Every time you shoot your bloodstream full of sugar, your body releases the hormone insulin, which transports the sugar straight into your body’s cells to use later as energy. When there’s more sugar than your organs need, the rest goes straight into your fat cells. Plus, the more often your blood sugar spikes, though, the less sensitive your body becomes to insulin’s effects, so sugar just piles up in your bloodstream—the marker of diabetes.
But if you’re getting those 1,500 calories from whole, healthy foods so that you get carbs, protein, fat, and fiber in every meal, you will keep your blood sugar levels stable and prevent insulin spikes and, eventually, resistance. Getting those calories from the right sources also makes sure you have the vitamins and nutrients your body needs for long-term weight loss, says Natalie Stephens R.D.N., L.D., a registered dietitian/nutritionist with Ohio State’s University Hospital East. For example, if you don’t get enough protein, you’re going to lose not just fat, but muscle (think: skinny fat).
Plus, actually burning calories is contingent on moving throughout the day. “Your body needs nutrients like carbs and good fats to fuel this activity, and you won’t find those in candy bars or soda,” Alish says. “Without proper nutrients, your body will tire quickly and make working out difficult, most likely closing the gap between the calories you eat and the calories you burn.”
Meanwhile, “saving” all of your calories for a big meal may or may not pan out well. Some research has shown that when you get your calories, even if that’s all at one meal, you could still lose weight. If you think about it, that’s the concept behind intermittent fasting: skip meals to eat fewer calories.
“My contention with this is that most people don’t have the self-discipline to truly eat only once daily. Most people snack or need other food times for energy,” Stephens says. “If someone has a fully functional stomach, it should be completely empty within four hours of eating. It’s natural to feel hungry every three to four hours.” Without enough fuel in your system, your blood sugar plummets, only to go through the roof once you finally do eat again. That’s why a 2015 study from The Ohio State University shows that skipping meals can increase blood sugar and insulin spikes, and contribute to that insulin resistance we talked about earlier. Meanwhile, Northwestern University research shows that eating the bulk of your daily calories at night can lead to weight gain—even if you aren’t eating more calories than you were before. Researchers believe eating at night may throw off your body’s circadian rhythms to lower your metabolic rate.
So, yeah, cut calories. But don’t hoard them all for late-night pizza binges.