WE’VE ALL BEEN there—you have a wedding, or a graduation, or a work conference that you told yourself you were going to get in shape for months ago. But time has come and gone, and you haven’t exactly given it your best effort. Before you know it, you have one week left to make something happen. You’re willing to do what it takes, but with such little time, it might not be enough to hit the goal you were looking to achieve. It begs the question—exactly how much weight can you lose in a week?
If you click on any weight loss transformation story, you’ll see incredible accomplishments of people shedding hundreds of pounds in a matter of months. Sometimes that’s done in a healthy manner, and sometimes people resort to extreme measures to shed those pounds. But if they can lose so much weight, surely there’s a way for you to lose just 10 pounds in a week, right?
The answer depends largely on your starting point. The more weight you carry, the more you’ll lose in a short amount of time. That’s especially true when you first start your weight loss journey, according to David Creel, Ph.D., R.D., a psychologist and registered dietitian at the Cleveland Clinic’s Bariatric and Metabolic Institute.
Some of this is simple math, but the biggest factor at play is that your body is fiercely protective of the weight you already have—so the longer you stay on a weight loss plan, the harder it becomes to see the numbers on the scale move.
Here’s why: As we shed pounds, our metabolism—our body’s internal fat-burning furnace—also slows down, causing us to burn fewer calories than before. “It’s like taking off a backpack,” says Dr. Creel. “Breathing requires fewer calories, walking down the street requires less energy—everything requires less energy.”
The less you weigh, the harder your body will cling to the weight you have, making it even more challenging for you to lose more.
“Unfortunately, our brain doesn’t have a scale saying, ‘when you reach a healthy weight, we’ll stop all this compensation,’” he says. “It doesn’t work that way.”
So even though everyone wants to know the maximum weight they can lose in a week—and everyone hopes for a significant number—the answer isn’t always straightforward. Here’s a breakdown of what’s realistically possible when it comes to weekly weight loss.
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How Much Weight Is Possible to Lose in a Week?
First off, there’s a distinction between how much weight you can lose in a week versus how much weight you should lose in a week—and trying to achieve the former can be risky.
“Wrestlers, boxers, people who have to make weight for a sport will often dehydrate themselves,” says Dr. Creel. “You can see people who may intentionally lose 20 pounds in a week—but it’s very dangerous.”
Here’s the thing about extreme diets, though—as much as you might desire to lose 10 pounds in the short-term, you’re not doing yourself any favors in the long run. Very low-calorie diets can cause dehydration, which means any weight you’re losing is primarily water weight, says Dr. Creel (and let’s face it, that doesn’t really count).
Moreover, extreme diets can lead to muscle loss, further hindering your metabolism. Muscles play a crucial role in burning calories throughout the day—the more muscle mass you have, the higher your metabolic rate.
“If someone follows a highly restrictive diet, they might lose 20 percent to 25 percent of their weight as muscle,” says Dr. Creel.
Extreme examples aside, Konstantinos Spaniolas, M.D., associate director of the Bariatric and Metabolic Weight Loss Center at Stony Brook University, suggests that losing one percent of your body weight per week is considered rapid but still reasonable.
Let’s say you start at 300 pounds—a goal of one percent fat loss per week means you’ll shed three pounds a week. That can be achievable. However, if you’re aiming to drop three pounds a week from a relatively lean 160-pound frame, you’ll likely encounter more challenges—or risk losing some muscle mass in the process.
How Much Weight Is Safe to Lose in a Week?
The general rule of thumb is about 1 to 2 pounds per week, says Dr. Creel. Even then, those numbers aren’t always consistent from week to week—it’s more of an average.
“A lot of people lose weight in a stair-step fashion, not a straight line,” says Dr. Creel. “They might drop four pounds in a week, and then their weight remains unchanged for two weeks, and then they drop two or three pounds.” If you want to lose fat without sacrificing muscle (or even gain muscle while losing fat), you’ll need to incorporate strength training into your routine. Research from Columbia University showed just how crucial it is for preserving muscle mass. Participants in the study cut calories and either did strength training or cardio workouts three times a week. After eight weeks, everyone lost more than 9 percent of their body weight. However, in the aerobic group, 20 percent of the weight loss came from lean tissue (largely muscle), while the resistance group only lost 8 percent of lean tissue while still achieving overall weight loss.
To preserve muscle, you should also ensure you’re consuming enough protein, which provides essential amino acids for muscle building. Dr. Spaniolas recommends consuming about .8 to 1 gram of protein per pound of body weight to retain muscle. There are various ways to include protein in your diet, including hearty vegan meals that offer more protein than a burger.
What Factors Affect Weight Loss?
Apart from your initial weight, there are other factors that can impact your weight loss journey. One of these factors is your history of dieting. Not only will smaller individuals burn fewer calories, says Yoni Freedhoff, M.D., author of “Why Diets Fail and How to Make Yours Work,” but complex hormonal and metabolic shifts also occur, making it more challenging to burn fat the longer you’ve been losing weight.
Scientists are still studying the mechanisms, but research has shown that people who have lost weight burn fewer calories compared to those who have never dieted. However, this doesn’t mean your efforts are futile—it simply implies that weight loss tends to be faster initially.
Lack of sleep can also disrupt hunger and metabolism hormones like leptin and ghrelin. In a small study published in the Annals of Internal Medicine, participants on a reduced-calorie diet slept either 5.5 or 8.5 hours a night. After two weeks, both groups lost a little over 6.5 pounds. However, those who slept more lost twice as much fat. Sleep is critical for overall well-being, and Men’s Health even compiled a list of the best strategies and products to help improve your sleep.
Of course, your diet will play a significant role in your weight loss journey. Dr. Spaniolas acknowledges that accurately estimating your daily caloric needs is complex but recommends using a chart or calculator from the National Institute of Health as a starting point. From there, you can reduce your calorie intake by about 500 calories per day to lose weight. However, it’s advised not to go too low initially. Even then, sustaining this calorie reduction may not be easy if you’re already lean and require fewer calories.
Watch what you drink as well: Alcohol can significantly increase your daily calorie intake if you’re not mindful of those extra calories. A study found that men consume an additional 433 calories on days when they drink a “moderate” amount of alcohol. It’s essential to consider alcohol calories when planning your weight loss strategy.
If you’re aiming to lose a substantial amount of weight or make significant changes to your body, investing in a body composition scale—which can measure fat, muscle mass, and more—might be beneficial. However, remember that it’s not all about the numbers. While you may want to achieve maximum weight loss in one week, what’s more important is making sustainable lifestyle changes that will improve your long-term health, according to Dr. Creel.
“There are other things to focus on besides one-week weight loss,” he says.