October 5, 2021

Is It Bad to Lose Weight Too Quickly?

Rapid weight loss can harm your health and lead to weight regain

Person in exercise clothes looking at their reflection in a mirror

When you’re ready to slim down, you want to make it happen now. But most health experts say rapid weight loss isn’t the way to go. It can sabotage your long-term weight loss goals and may hurt your health, too.


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Why is it bad to lose weight quickly? Endocrinologist and obesity specialist Marcio Griebeler, MD, explains why slow and steady wins the weight-loss race — and how to do it.

What is rapid weight loss?

There’s no magic number that qualifies as “rapid weight loss.” Your weight, age and activity level determine what that term means for you.

Don’t worry too much about the number of pounds you should (or shouldn’t) lose. Instead, look at the diet plan you’re following to lose weight. Extreme diets with lofty promises usually fall under the “rapid weight loss” category.

“Avoid super restrictive diet plans because they’re difficult — if not impossible — to keep up over the long term,” says Dr. Griebeler. “If the diet plan isn’t something you can stick to for months or years, it’s probably a fast weight loss plan. And those plans and gimmicks aren’t a healthy, sustainable way to lose weight.”

A more moderate goal of losing 1 to 2 pounds per week tends to be more successful over the long haul.

Risks of fast weight loss

It’s hard to resist the lure of rapid weight loss. Be 10 pounds lighter by next week? Yes, please. But don’t give in to the flashy ads. Most of the time, those diet plans are bad news for your health.

Your metabolism shifts to low gear

Your metabolism is your body’s calorie-burning process. And a metabolism that’s out of whack can damage your body’s ability to keep the weight off.

“When you lose weight too quickly, your body slows down its calorie-burning process,” explains Dr. Griebeler. “That is your body’s way of trying to ensure you don’t starve. You might lose a good amount of weight right away, but your metabolism quickly goes into survival mode.”

The change in your metabolism is a key reason why people regain weight after trying rapid weight loss plans. When you go back to eating a regular diet, your metabolism isn’t used to that many calories — and the pounds come back.


You lose muscle mass

When you cut way back on calories, you might see that number on the scale drop like a rock. But it’s not just fat you’re losing. You’re also losing muscle.

“Sudden and severe calorie restriction will make you lose muscle mass as well as fat,” says Dr. Griebeler. “It’s harder to lose weight when you don’t have enough muscle mass because muscles burn lots of calories.”

Slower weight loss combined with exercise, on the other hand, gives your body time to lose fat while keeping your muscle mass. And bonus: You keep your muscles’ calorie-burning power intact.

You miss out on important nutrients

Your body needs a certain amount of fat, protein and carbs to function. It also needs a whole range of vitamins and minerals. When you slash calories or cut out entire food groups like carbs or dairy, you risk:

“There’s nothing wrong with cutting calories if you’re eating a variety of nutrient-rich foods,” says Dr. Griebeler. “Your diet should contain a wide variety of healthy, whole foods. Don’t try to cut more than 500 calories a day.”

You’ll likely quit your diet

When you go for fast weight loss, you may find that it gets harder — not easier — to keep losing weight. A couple of weeks in, you’ll likely feel famished all the time. The temptation to crawl into bed with a box of cookies is real.

Don’t blame a lack of willpower. It’s your hormones, and they’re doing exactly what they were designed to do.

“Cutting too many calories too quickly triggers hormonal changes that make you want to eat,” says Dr. Griebeler. “Even a very determined person will find it difficult to overpower those hunger hormones. These fast hormonal changes make you so hungry that they set you up for diet failure.”

Healthy (and steady) weight loss should be your goal

There’s no single diet that works for everyone. But these general guidelines can help you lose weight — and keep it off — in a healthy way.


Build muscle while you lose weight

Healthy weight loss isn’t just about what you eat. You need physical activity if you want maximum results.

Cardiovascular exercise like walking burns calories, but strength training is just as important. When you lift weights or do resistance training, you increase muscle mass. And when you have more muscle mass, you:

  • Burn more calories, even at rest.
  • Improve your balance and reduce your risk of falls.
  • Reduce joint pain and symptoms of arthritis so you can keep moving and losing weight.
  • Strengthen your bones and reduce your risk of fractures and osteoporosis.

Make sleep a priority

Ever notice that when you’re exhausted you want to eat more? When you’re tired, your hunger hormones barge in and ruin your chances of bypassing that donut. If you’re regularly missing out on sleep, even the best weight loss plan is going to feel impossible.

“Aim for at least seven hours of quality sleep each night,” says Dr. Griebeler. “If you consistently have trouble sleeping, talk to your doctor. Many people who have sleep disorders don’t know it — and sleep disorders are treatable.”

Find a balance

Think about your diet plan and whether you could do it for the rest of your life. Cutting a couple of hundred calories a day? Doable. Never having a bowl of ice cream again? Probably not.

“The best diet is one you will stick to,” says Dr. Griebeler. “Changing our habits is hard, but it can be done. Choose a diet plan that allows you to have an occasional piece of chocolate or slice of pizza. It’s much easier to keep doing these types of plans for months and even years.”

Fast results are fun for a while, instant gratification isn’t best when it comes to weight loss. Go slow with dropping pounds so you can be healthier today and stay that way for years to come.

Related Articles

variety of food groups containing manganese and magnesium
November 30, 2023
Manganese vs. Magnesium: Two Important Minerals With Key Differences

They’re both essential minerals but do different jobs in your body

holy basil leaves, known as tulsi, on wooden spoon
November 30, 2023
The Benefits of Holy Basil (Tulsi)

This herb offers different potential benefits from the basil you find in pesto

cool tropical smoothie with straw
November 30, 2023
Recipe: Cool Tropical Smoothie

A zesty thirst-quencher that’s dairy-free and vegan

salmon and broccoli over rice
November 29, 2023
6 Foods To Eat for Healthy Joints

Fish, cruciferous veggies, turmeric, yogurt, ginger and green tea all reduce inflammation

skillet of ground turkey stroganoff
November 28, 2023
Recipe: Healthy Turkey Stroganoff

A hearty dish that’s easy to put together

Top view of a bowl of chili topped with sour cream and jalapeños with tortilla chips for dipping.
November 24, 2023
Recipe Adventure: How To Build a Better Bowl of Chili

From meat to beans, we’ve got some ideas to help you create the perfect-for-you chili recipe

Spearmint tea in a glass see through cup with spearmint leaves scattered on the saucer and background.
November 22, 2023
3 Health Benefits of Spearmint Tea

This subtly minty beverage can help balance hormones and loosen stiff joints

Overhead closeup of cauliflower pseudo mashed potatoes in a bowl on a wooden table.
November 21, 2023
Recipe: Cauliflower Mashed Pseudo Potatoes

A creamy mashed cauliflower that’s sure to please

Trending Topics

group of hands holding different beverages
November 14, 2023
10 Myths About Drinking Alcohol You Should Stop Repeating

Coffee won’t cure a hangover and you definitely shouldn’t mix your cocktail with an energy drink

Person applies moisturizer as part of their skin care routine after a shower.
November 10, 2023
Korean Skin Care Routines: What You Need To Know

Focus on the philosophy — replenishing and respecting your skin — not necessarily the steps

glass of cherry juice with cherries on table
November 8, 2023
Sleepy Girl Mocktail: What’s in It and Does It Really Make You Sleep Better?

This social media sleep hack with tart cherry juice and magnesium could be worth a try