Lose Weight Fast: How to Do It Safely

Last Editorial Review: 11/17/2010

Sick of crash diets and fad diets? Follow these healthy tips for rapid weight loss.

By Kathleen M. Zelman, MPH, RD, LD
WebMD Feature

Reviewed by Brunilda Nazario, MD

You've heard it time and again: fad diets don't work for permanent weight loss. But what about those times when you really need to lose some weight fast? It's hard to pass up the promise of crash diets like the Lemonade Diet, Cabbage Soup Diet, or Lose 21 Pounds in 21 Days when your mission is to squeeze into a new outfit in time for a reunion, wedding, or other special event.

So what's wrong with dropping 20 pounds fast so you can wow your friends and family with a svelte new shape?

The truth is that nothing is wrong with losing weight rapidly -- as long you do it the right way, says Michael Dansinger, MD. He's the medical doctor for NBC's The Biggest Loser show, which spotlights quick and dramatic weight loss.

"In theory, one could drop as much as 20 pounds in a week following a very ambitious eating and exercise plan, devoting more than seven hours per week to rigorous exercise, and under a physician's care like we do on the television program," he says.

But even if you can't drop everything to go to weight loss "boot camp," you can safely lose 3 or more pounds a week at home with a healthy diet and lots of exercise, says weight loss counselor Katherine Tallmadge, RD.

In fact, having a goal like looking great at a wedding or reunion can be a great motivator, as long as you follow a weight loss plan that you can keep up after the special event.

But you need to plan ahead and allow enough time to make changes to your shape.

"Don't wait until one week before the reunion to try and lose 10 pounds," advises Tara Gidus, MS, RD, team dietitian for the Orlando Magic.

How to Lose Weight Fast

Losing weight is a simple mathematical formula: You need to burn more calories than you eat. Experts generally recommend creating a deficit of 500 calories per day through a combination of eating fewer calories and increasing physical activity. Over the course of a week, this should yield a loss of about 1-2 pounds of fat.

If you want to lose weight faster, you'll need to eat less and exercise more. Bottom line: 1,050 to 1,200 calories and one hour of exercise a day (but be sure not to dip below this calorie level for safety's sake). On this type of plan, you can expect to lose 3-5 pounds the first week, or more if you weigh over 250 pounds.

"Dieters who follow the plan can lose 2 pounds from diet and 1 pound from exercise each week, and even more if they have more to lose, because the more fat you have to lose, the faster it comes off," says Dansinger.

You may lose even more weight initially if you limit salt and starches.

"When you reduce sodium and cut starches, you reduce fluids and fluid retention, which can result in up to 5 pounds of fluid loss when you get started," explains Dansinger.

Diets for Fast Weight Loss

When it comes to weight loss, calories count the most, says Dansinger. He recommends cutting back to a daily level of 7 calories per pound of your current body weight (which for a 200-pound person, for example, would be 1,400 calories), but no less than 1,050 calories/day (the lowest level that can be done safely at home). Dietitians more typically recommend 1,200 calories as a daily minimum.

Dansinger advocates a diet that minimizes starches, (even healthy whole grains should be controlled), added sugars, and animal fat from meat and dairy foods. For rapid weight loss, dieters should eat mainly fruits, veggies, egg whites, soy products, skinless poultry breasts, fish, shellfish, nonfat dairy foods, and 95% lean meat.

He notes that there are other ways to control calories, such as minimizing total fat, but believes that tends to be more challenging than his suggested weight loss plan.

Other experts interviewed by WebMD recommended tactics including drinking lots of water, eating plenty of protein, and keeping a food journal.

"Eat enough protein and distribute it evenly through your meals to minimize muscle loss and maximize fat loss," says Tallmadge, author of Diet Simple, who also advises clients to swap out carbs in favor of veggies.

American Dietetic Association spokesperson Dawn Jackson Blatner, RD, recommends:

  • Eat plenty of low-calorie vegetables to help you feel full.

  • Drink plenty of water so you don't confuse hunger with thirst.

  • Clear the house of tempting foods.

  • Stay busy to prevent eating out of boredom.

  • Eat only from a plate, while seated at a table.

  • Always eat three meals and one snack daily -- no skipping meals.

Weighing yourself daily and tracking your food intake can also help you keep focused, experts say.

"Even if you write it down on a napkin and end up throwing it away, the act of writing it down is about being accountable to yourself and is a very effective tool for weight loss," says Bonnie Taub Dix, MA, RD, a food and nutrition blogger for USA Today.

Although it won't actually help you lose weight, Blatner, author of The Flexitarian Diet, says that eating fennel seeds, ginger, parsley, peppermint, pineapple, and yogurt with honey one to three days before the big event can help you de-bloat and keep your tummy feeling flatter.

Exercising for Fast Weight Loss

Even if you are currently exercising, you'll need to kick it up a notch if your goal is rapid weight loss, says Gidus. A study published in the Archives of Internal Medicine indicated that losing weight requires close to an hour a day of moderate exercise.

That fits in with Dansinger's recommendation of seven hours per week of cardio exercise leading up to your special event.

"Cardio burns the most calories, so it is ideal for fast weight loss, but afterwards you need to include a few hours a week of strength training," he says. To burn the most fat, try to break a sweat after your warm-up and keep sweating for the entire hour, says Dansinger.

Most everyone can do an hour a day, but the intensity of your workout will depend on your current state of fitness. Experts recommend gradually increasing exercise intensity to avoid injury.

When you can't do cardio, Tallmadge recommends doing strength training at least twice weekly, working all your major muscle groups, and fitting in at least 15,000 steps a day (get a pedometer to keep count).

Gidus suggests doubling up on your exercise routine: "Do a morning and evening workout, and if you don't have time to do two a day, expend more calories in the workouts you are currently doing."

Another option is to incorporate interval training. The new South Beach Supercharged plan by Arthur Agatson, MD, promotes adding high-intensity intervals to workouts to burn more calories in less time.

"Interval training allows people to work harder without having to spend the entire time at the higher level, and over time, the more you do it, the easier it becomes to burn more calories," says Blatner.


Weight loss occurs in the belly before anywhere else. See Answer

Fad Diets and Crash Diets

Many people don't have the time to do the rigorous amount of exercise required to lose weight quickly, and so turn to fad diets. But keep in mind that if a diet plan sounds too good to be true, it probably is. So steer clear of programs that promote pills, laxatives, fasting, or potions, and any that promise weight loss faster than 2-3 pounds per week.

The truth is that cutting calories below 1,050 per day is counterproductive, because you need strong muscles to be able to exercise effectively.

"When you eat too few calories you lose fat but also precious muscle, which is the worst thing you could do because it slows your metabolism and makes it more difficult to increase exercise intensity or duration," says Dansinger.

And what about over-the-counter (OTC) diet pills? Except for the OTC version of Alli, most respected experts do not recommend them.

"Diet pills are either ineffective or extremely dangerous, and not recommended," says Dansinger.

The bottom line? Weight loss experts agree that any rapid weight loss diet should be identical to a long-term, sustainable plan -- and not a fad diet. And fasting or cutting calories below 1,050 are not appropriate for the long term unless you are under a physician's care.

Health Solutions From Our Sponsors


Michael Dansinger, MD, Tufts Medical Center diabetes reversal program; nutrition adviser, The Biggest Loser.

Katherine Tallmadge, MA, RD, spokeswoman, American Dietetic Association; author, Diet Simple.

Bonnie Taub Dix, MA, RD, director, BTD nutrition consultants; co-author, Kosher by Design, Lightens Up; food and nutrition blogger, USA Today.

Dawn Jackson Blatner, RD, spokeswoman, American Dietetic Association; author, The Flexitarian Diet.

Tara Gidus, MS, RD, spokesperson, American Dietetic Association; team dietitian, Orlando Magic.

Arthur Agatston, MD, cardiologist; associate professor of medicine, University of Miami's Miller School of Medicine; author, South Beach Diet Supercharged.

Archives of Internal Medicine, July 28, 2008.

National Institute of Health: "Obesity."

Reviewed on November 17, 2010

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