How to Lose 20 Pounds Fast: Is It Even Possible?

For various reasons, many people find themselves wondering how to lose 20 pounds quickly.

Having reasonable expectations can help protect your health and also ensure long-term success.

So, how long should it take to lose 20 pounds (about 9 kilograms)? Below, we discuss if it’s possible to do in two months or less.

How to Lose 20 Pounds in 2 Weeks?

How to Lose 20 Pounds in 2 Weeks

Simple math reveals that it’s unrealistic to lose 20 pounds in 2 weeks.

Weight loss occurs when you eat fewer calories than you burn. The number of calories you burn each day is called your total daily energy expenditure (TDEE). It’s determined by your age, height, weight, activity levels and other factors.

You can estimate your TDEE using this calculator.

Generally speaking, you need to burn about 3,500 more calories than you eat to lose one pound. This can be done with a combination of diet and exercise, though studies suggest that diet is more effective. In other words, you’ll need to eat fewer calories (1).

To lose 20 pounds in 2 weeks, you’d need to create an average daily deficit of 5,000 calories from your TDEE. This is how that’s calculated:

3,500 calories per pound  x 20 pounds = 70,000 total calories

70,000 calories / 14 days = 5,000 calories per day

This is very difficult to do considering that:

  • The average man burns 2,400 calories per day and the average woman burns 2,000 calories per day.
  • Most people eat far fewer than 5,000 calories per day. Americans, who have the highest calorie intake of any population, eat an average of 3,800 calories per day.

To put this into perspective, even a person who eats a measly 1,000 calories per day would need to burn 6,000 calories daily to lose 20 pounds in two weeks. The average person would need to burn the calorie equivalent of running 60 miles per day for 14 days.

If that hasn’t convinced you, realize that crash diets are dangerous. Studies have linked very low-calorie diets with decreased muscle mass, plus a 12% greater risk of gallstones. They’re also not sustainable, which increases the likelihood of weight regain over time (2, 3, 4, 5).

Trying to lose 20 pounds in 2 weeks is simply not worth the risk.

Summary: It’s unrealistic and dangerous to attempt a 20-pound weight loss in 2 weeks. Doing so would require a deficit of 5,000 calories per day, which is far more than what most people eat and burn in a day.

Can You Lose 20 Pounds in 1 Month?

Can You Lose 20 Pounds in 1 Month

Losing 20 pounds in 1 month may be easier than 2 weeks, but it’s still unrealistic for most people.

Once again, it comes down to your TDEE and simple math. To lose 20 pounds in 1 month, you’d need to create an average deficit of 2,500 calories per day for 4 weeks.

This might be possible for larger men. Let’s look at an example:

A 20-year-old male who is sedentary, 74 inches (188 cm) tall, and 350 pounds (159 kg) has an estimated TDEE of 3,201 calories per day. His TDEE would increase to just over 4,000 calories per day if he added moderate exercise. He could lose 20 pounds in 1 month if he followed a 1,500-calorie diet, but this would be difficult.

A 20-pound weight loss in 1 month is much less likely for smaller women, who typically eat less and burn fewer than 2,500 calories per day.

Summary: A weight loss of 20 pounds in one month is unlikely unless you have a very high TDEE.

Can You Lose 20 Pounds in 2 Months?

Can You Lose 20 Pounds in 2 Months

Losing 20 pounds in 2 months is challenging, but not impossible.

Doing so would require an average daily deficit of about 1,250 calories for 2 months.

This time, let’s look at a 25-year-old sedentary female, who is 68 inches (173 cm) tall and weighs 210 pounds (96 kg). This woman could increase her estimated TDEE from 2,095 calories per day to 2,700 calories per day by adding moderate exercise.

This means, a 1,500-calorie diet would help her lose 20 pounds in 2 months, or at least come close, since she’d have a daily deficit of 1,200 calories with moderate exercise.

Keep in mind that weight loss is typically more rapid in people who have more weight to lose. TDEEs are higher in people who are taller and weigh more, simply because it takes more energy to move and sustain their bodies.

In other words, smaller people may struggle to lose 20 pounds in 2 months—and may not even need to lose this much anyway.

Summary: Taller adults with a bit of weight to lose may be able to lose 20 pounds in 2 months. This would require an average calorie deficit of 1,250 per day.

Tips for Losing 20 Pounds

Tips for Losing 20 Pounds

Deadlines aside, 20 pounds is a great weight loss goal for you depending on your individual needs.

If you weigh 200 pounds or more, losing 20 pounds can reduce your risk for diabetes, heart disease and other health problems (6).

Here are a few tips to get you started:

  1. It’s always easier to lose weight when you have more time to reach your goals. Start several months in advance if you know you have a big event on your calendar.
  2. Focus on building healthy habits for long-term success. Here are 77 proven ways to lose weight.
  3. Track your calories using an app like MyFitnessPal. Studies suggest that tracking can actually increase your odds of success (7).
  4. Consider a low-carb meal plan if you’re on a tight schedule. Low-carb diets promote rapid weight loss because the body sheds water weight as it burns up stored carbohydrates. In one study of 377 overweight or obese adults, participants lost an average of 7 kg (15.4 pounds) after just 4 weeks on a very low-carb diet (8). Just remember, you may not lose as much if you have a lower TDEE or can’t stick with the diet. Water weight comes back quickly after even a few high-carb meals if you’ve been following a low-carb diet.
  5. If you have more time, you could try a 1,500-calorie diet (or a 1,200-calorie diet, if you’re a small or sedentary woman).
  6. If you’re not on a tight deadline, you should choose a style of eating that you’ll be able to stick to long-term. Diet adherence is an important predictor of long-term success (9).

Summary: For many overweight or obese adults, 20 pounds is a great weight loss goal. A low-carb diet is your best bet for quick results, but it’s better to give yourself plenty of time to reach your goal. It’s best to choose a diet plan that will be easiest for you to follow long-term.

How Long Does It Take to Lose 20 Pounds?

There’s no universal answer to this question.

If you’re wondering how to lose 20 pounds (approx. 9kg), you’ll want to set a realistic time frame for getting there.

Weight loss is generally more rapid among men and women with more weight to lose. Therefore, those with obesity may reach their weight loss goal in just a few weeks. Leaner adults may need more time.

A low-carb diet can be a good approach for those seeking quick results. Many low-carb dieters lose several pounds of water weight in the first few days of the diet, with more gradual weight loss in the following weeks.

In general, though, you should expect your weight loss journey to take at least two months. Anything less than this can be unrealistic and possibly even dangerous.

Choosing a diet that’s easy to stick with will increase your odds of long-term success and make the process much more enjoyable.



About Kimberly Yawitz (Registered Dietitian Nutritionist)

Kim Yawitz is a registered dietitian and nutritionist in St. Louis, Missouri.

She currently works with sports nutrition and weight management clients for a private practice. Prior to that Kim worked as an inpatient clinical dietitian, developing nutrition care plans for patients with health concerns ranging from autoimmune disease to critical illness.

Learn more about her on the About page