But many experts emphasize a key point to weight loss: You have to expend more calories than you consume. No matter what you’re eating, you have to burn more calories than you take in. This is the “calorie deficit” approach to weight loss, which is the oldest weight loss trick in the book and has been having a moment on TikTok recently. But is it really that simple? We asked the experts—here’s what you should know.
What is a calorie deficit?
First things first: The body needs energy. All the cells in your body need energy in order to function and keep things clicking along. Your body stores energy in the form of fat, and it can pull from those stores. But it also gets energy from the food that you eat. “So if you aren’t eating enough food, your body is going to go deep into the reserves that are your fat stores,” explains Debbie Petitpain, MS, RDN, a registered dietitian and spokesperson for the Academy Nutrition and Dietetics. From a weight loss perspective, that’s a good thing. But can you achieve that and keep it going? Can you stick with a low-enough calorie diet to lose the weight that you want to lose, and then keep it off? It can be hard to stick to a low-calorie eating plan over the long-term, and you may start to feel dissatisfied with what you’re eating. Or as Petitpain puts it, ask yourself: “How hangry are you going to be in the process?”
Calorie deficit to lose weight
So back to the big question: is weight loss really as simple as burning more calories than you take in? “It’s not that simple,” says bariatric surgeon Kuldeep Singh, MD, MBA, director of the Maryland Bariatric Center at Mercy. “But it is essential that we consume less than we put in. If we don’t do that, no program is going to work,” he adds. And yes, you’ll notice the numbers going down on the scale if your body consistently has to break down its stored fat, but there are a lot of variations that can affect the process — and it can vary from person to person, too. Factors like hormone levels and stress, can interfere with your body’s ability to lose weight. So can your innate metabolism.“With a high metabolism, you’ll need to take in more calories to maintain your weight. A person with a low metabolism will burn fewer calories and have to eat less to avoid becoming overweight,” says registered dietitian Rachel Paul, PhD, RD. “Putting the theory into practice is way more challenging and way more complex because your body has many systems to fight change,” says Petitpain. Your body may realize that you’re losing weight, and it may try to counteract the effect. “It’s all because it’s trying to go back to that place of balance,” says Petitpain. “Bodies like balance.” This is called metabolic adaptation, notes Singh, and it occurs when your body becomes more efficient and your metabolism slows down. So while you can lose weight on a plan that requires you to get by on a very reduced calorie total, it’s really a short-term solution. In the long term, Singh says, it will become less effective. Ultimately, you need to think “sustainable.” You’ll need to combine calorie reduction with exercise and stress reduction if you want to keep the weight off, and some research suggests that you might want to also consider the size of your meals and even when you eat them.
How to calculate calorie deficit
Calories are units of energy, so they represent how much energy you could obtain from eating or drinking something. Your body burns calories through exercise, digestion and other basic bodily functions. A moderately active woman in her 30s or 40s needs about 2,000 calories per day, according to the 2015-2020 Dietary Guidelines for Americans . If she’s considered more active, she would need about 2,200 calories per day. Men need a few more calories per day, on average. And these numbers tend to decrease as we age. But since everyone’s body (and metabolism) is different, you may burn calories at a different rate than someone else. The basic math goes something like this: You need to burn 3,500 calories to lose one pound of weight. If you shave 500 calories off your typical daily caloric intake, in theory you could lose one pound per week. If you reduce your calorie intake by 700 calories per day, you could lose a little more. Because your caloric needs may vary, it’s worth it to check in with a healthcare professional to make sure you’re approaching the situation in a way that’s safe and healthy for you.
Don’t forget about nutrition
Something else to consider if you’re restricting your calorie intake and boosting your activity level: Are you getting the nutrition you need from the food you’re eating? You do need to be mindful of what you’re eating, so you’ll get the right amount of macronutrients—that is, carbohydrates, protein, and fast—for your body to be healthy. If you eat the right amounts for you, it will also rev up your metabolism and keep you full until your next meal, says Tamar Samuels, MS, RD, cofounder of Culina Health. Think about it this way. You could eat the same amount of calories in s’mores or vegetables and whole grains, but which is the better choice? “We always say all calories aren’t created equal,” says Samuels. “If you ate a 100-calorie pack of Oreos, that would get digested quickly and leave you not feeling satisfied, but if you ate half an apple and 15 almonds, you would have fiber, fat and protein to help slow down digestion and keep you full for longer and have you not craving junk.” A nutrient-dense diet can send signals to your brain that you’re full and help satiate your appetite, says Paul. And that can help you avoid eating more than you should. Next up, can you lose weight from exercise alone?
Sources
Debbie Petitpain, MS, RDN, a registered dietitian with the Academy of Nutrition and DieteticsKuldeep Singh, MD, MBA, a bariatric surgeon and director of the Maryland Bariatric Center at MercyTamar Samuels, MS, RD, a registered dietitian and cofounder of Culina Health.Rachel Paul, PhD, RD, a registered dietitian and the College NutritionistJournal of Nutrition and Metabolism: “A review of weight control strategies and their effects on the regulation of hormonal balance.“Journal of the American College of Nutrition: The Thermic Effect of Food: A ReviewHealth.gov: Dietary Guidelines: 2015-2020
