Experts Explain How Much Weight You Can Expect to Lose in a Week

Photo credit: kali9 - Getty Images
Photo credit: kali9 - Getty Images

From Prevention

Listen, I totally get why you’re searching this topic.

Maybe you have an reunion that snuck up on you, and the newly single ex you should have married in the first place will be there. Why wouldn’t you want to feel sleek and adorable in your sexiest dress? Or perhaps you’re headed to Cancun and think you’ll have more fun pretending to be Helena Christensen circa 1991 frolicking in the surf if you looked a little more like her. Sure.

And I will answer your question—I pinky swear.

But as someone who has beaten back an eating disorder, I gotta point out that thinking of weight loss as a week-to-week calculus can suck you in to unhealthy weight control practices.

“We’re not into double workouts, laxatives, counting and aggressively skipping calories, skipping meals or anything that leaves you feeling poorly,” says Lauren Slayton, R.D., founder of Foodtrainers. “I guess that needs to be said.”

But since people do crave a quick slim-down, is there a way to do it wisely? Foodtrainers offers a one-week program that supports clients when they have a big-deal reason to drop a few pounds fast. “A week of pre-event eating can be confidence boosting as long as it isn’t insane, extreme or punitive.”

Thanks for the reminder. So how much weight can I lose in a week?

The simple math goes like this: How much fat you lose over the course of a week has to do with how many more calories you burn than you take in. A pound of fat is accumulated when you eat 3,500 calories more than you burn; likewise, if you eat 3,500 calories a week less than you burn—all else being equal—you’ll lose around a pound. If you manage a deficit of 7,000 calories, you’ll lose two. The Centers for Disease Control and Prevention says that one to two pounds in a week is a safe amount to lose if you’re doing it gradually and steadily.

1-2 pounds in a week is a safe amount to lose, per the CDC.

But is it possible to lose more in a week?

Slayton’s one-week plans can result in up to 5 pounds off (less if you're a small person with not much to lose). That’s according to the number on the scale. “But you’re not losing more than a couple pounds of body fat per week so it’s a little fat a and a little fluid loss,” she says. Clients cook mostly at home as opposed to eating out, and eat lots of vegetables and fish, and cut booze and sugar out entirely. “We don’t advise weeks like this more than once a quarter or season—it’s not how to eat day in and day out.”

That’s because even if you’re not at risk of an eating disorder, being too restrictive has a rebound effect, says Caroline Apovian, M.D., the director of the Center for Nutrition and Weight Management at Boston Medical Center. “People who try to lose weight in a week or a month are going to gain it back,” she says. Plus, gaining and losing weight in succession is rotten for your health.

Besides, you lose muscle mass (in addition to fat) when you go for quick weight loss, and it’s muscle that helps you burn calories; that means your metabolism will slow and it’ll be harder to keep weight off—even if you restrict caloric intake, says Dr. Apovian.

So what should I do if I want to look thinner in a week?

Aside from any weight you might lose, add what Slayton calls “delicious de-bloaters:” avocado, asparagus, dandelion tea, lemons, and parsley. “Are those helping you lose more than water? No. But do they make you feel a little less bloated and puffy? Sure.”

Then—after you and your ex have happily reunited or you’re back from your beach vacation—go back to your regularly scheduled healthy but not-too-strict eating. Of course, we all know that doing a quick one-off sprint to thinner means you won't be able to sustain all of it, says Slayton, and that's OK: You achieved your purpose, and as long as you don't go nuts making up for food not eaten, you may even be able to keep off some of the weight off, she says.

Bottom Line:

Upping your weight loss ante short term, as long as you do it healthfully, is an OK thing to do a few of times a year. “This is not the way I have clients eat 48 weeks of the year—one is marriage and the other is like a one night stand or weekend fling. No judgement, but they’re just totally different.”


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