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What Happens to Your Body When You Only Eat Once a Day

This toxic dieting belief is not advised by real medical experts. Here's why.

Let's get this out of the way first, shall we? It's not healthy to restrict yourself. Yes, it's good for weight loss to find a healthy balance of calories to eat and calories to burn, but it's also healthy to eat a consistent amount of nutritious meals throughout the day. Food provides our bodies with all of the nutrients it needs to survive, and by only eating once a day, you're not allowing your body the chance to get all of those nutrients it needs.

Nevertheless, many "experts" that promote toxic diet culture will try to promote disordered ways of eating in order to help people lose weight quickly, and one of those suggestions is to only eat once a day. Yes, this will restrict your calorie intake, and eating fewer calories can help with weight loss. But there's so much more that happens to your body when you only eat once a day, and most of it is negative. Plus, restricting your body to only one meal will actually make weight loss even harder.

In order to show you why only eating once a day is bad for your body, we spoke with a few registered dietitians and certified medical experts who properly broke down what your body will experience with such serious calorie restriction. Here's why none of them advise you to eat once a day, and if you're looking for healthy meals to add to your diet, we highly suggest these 100 Easiest Recipes You Can Make.

Eating once can lead to overeating.

happy woman eating pasta for dinner

If the term "calories" is actually a measurement of energy, then by not giving your body a sufficient amount of calories, you are quite literally cutting the energy you are giving to your body.

Many dietitians agree that if you're only eating once a day, you are likely going to overeat during that one meal because, at that point, your body is ravenous and in need of quick energy.

"Eating once a day sets you up for deprivation and then overeating—one of the worst things you can do if you are trying to lose weight," says Lisa Young, PhD, RDN, author of Finally Full, Finally Slim. "Once you do eat your 'one meal,' you often keep eating because you were deprived of food all day. Plus it can be a lot for your body to handle at once."

So even if your intention is to restrict calories, it can still be easy to consume a lot of calories in one sitting—especially if you're going for non-nutritious items like fatty foods and processed snacks.

Learn more about the Emotions That Lead to Overeating and Weight Gain.

Eating once a day slows down your metabolism.

Woman pushing plate of pizza away to skip a meal

"If you go long periods of time without eating, your metabolism actually slows down to hold on to energy," Brenda Braslow, RD, MS with MyNetDiary. "It can defeat your efforts to cut back on calorie intake."

Without a high-functioning metabolism, losing weight becomes a lot harder. Instead, focus on these 31 Healthy Meals That Boost Your Metabolism for Weight Loss.

Your body will think it's starving and go into "starvation mode."

hungry man

Your metabolism is there to burn calories, making it easier to lose weight. But if you only eat once a day, it will slow down in order to hold that "energy" for later use.

"Our body starts to go through a process of metabolic adaptation where your metabolism slows down significantly to match what you are intaking, many times also described as 'starvation mode,'" says Ricci-Lee Hotz, MS, RDN at A Taste of Health and Expert at "Instead of using what your body needs when you eat and getting rid of the extra, it is going to store what you intake as fat to ensure it has fuel that it can use while you are not fueling your body."

Your body will start shutting down.

eating dinner

Along with slowing metabolism and increased hunger, your body will also start to see a whirlwind of negative side effects if you're not giving it the nutrients it needs.

"The other negative effects can include having your blood sugar drop so you feel weak and shaky, nutrient deficiencies, exhaustion, binge eating at the one time you do eat, weight gain, or if you do keep your calories low at your one meal, heart problems, hair loss, cold intolerance, and more," says Hotz.

Your body won't get enough nutrients.

eating salad

"One primary reason I discourage dieters from eating just one meal a day is the lack of nutrient density they are likely consuming," says Trista Best, MPH, RD, LD from Balance One Supplements. "When eating just one meal a day it is more likely that consumers will turn to high calorie, low nutrient foods like pasta and high-fat animal proteins. This is because their glucose has dropped to such a low point that they begin craving carbohydrates and often turn to quick processed options."

Plus, Best points out that if you're filling up on those quick carbohydrates in order to feel full, you aren't giving your body the nutrients it needs.

So what's the solution? It will obviously depend on your body, but many dietitians recommend eating every three or four hours (or at least eating three meals), and following the proper nutrition guidelines to set up a healthy meal. If you're not sure what the proper caloric intake your body needs, here's a calculator—or even talk to a medical professional to find out the right diet for your specific body.

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Kiersten Hickman
Kiersten Hickman is a freelance health and nutrition journalist. Read more about Kiersten
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