How Much Body Fat Can You Really Lose In A Week?

Negative publicity has always surrounded certain diet programs past and present. The genuine concern from caring individuals for others following dubious programs has sometimes been wrongly perceived as negativity or attacks. I share the concern that extreme dieting (Very Low Calorie Diets) done long term – and for some even short term – can be detrimental to body composition and health. So I feel compelled to say something.

Very low calorie diets have a place in the medical arsenal of bariatric specialists to treat extreme cases of morbid obesity. If you’ve watched the Discovery Channel shows Inside Brookhaven and Big Medicine you’ll have noticed the use of medically supervised 1200 calorie diets for treatment of morbid obesity and to prepare gastric bypass patients before surgery.

On the other hand, use of these diets long term or for losing moderate amounts of weight without medical supervision can be dangerous and tend to back fire. Starvation diets lower metabolism and lead to later weight gain if a normal consumption of calories is resumed.

“Proper diet will increase and speed up your metabolism. It is important to never skip a meal or go on any type of starvation diet. You should always eat healthy snacks between meals. The idea is to eat frequently to prevent hunger pangs, and to keep your energy levels consistent which in turn will increase and speed up your metabolism.

Our bodies were designed with a survival mechanism just in case there is a time of famine. Because of this mechanism, it is easier for the body to store fat. If we go on any calorie deficit diet or some type of starvation diet you can forget about increasing your metabolism because our body's metabolism decreases in order to conserve energy. In this mode, it is much easier for the body to store what we eat as body fat and burn energy from muscle tissue. Since muscle tissue burns a higher amount of calories, the less we have the lower our metabolism will be.” - From How To Speed Up Your Metabolism

I doubt the commercial success of any program will be damaged by all the fuss of positive or negative press or discussion surrounding it. There will always be plenty of dieters seeking fast solutions and quick fixes. And as they say in Hollywood, “There’s no such thing as bad publicity.”

But I can’t help but cringe when I read of dieters who lose more than two or three pounds of scale weight in a week (like 7 or 10 pounds) and they’re thrilled about it. Chances are they lost a lot more than body fat. Others lose a healthy and reasonable amount and become upset, frustrated and discouraged that the scale “only” went down a pound or two. There is a prevailing attitude these days among dieters of all styles that losing weight rapidly is healthy and desirable.

This just isn’t so. The Biggest Loser is guilty of glamorizing fast weight loss and making people believe it’s a reasonable goal. But most people overlook just how intensely these people trained and how strictly they ate clean under professional supervision. This is why some contestants gain some or all of the weight back. Very few people have time, energy, and income to train like a professional athlete all the time.

Losing no more than 3 pounds a week if you’re obese or overweight, or losing no more than ½ pound to 2 pounds a week if you’re closer to goal, is exactly what you should be aiming for. If you’re losing more scale weight than that – and particularly if you’re losing weight rapidly like a Biggest Loser contestant - you’re risking muscle loss, excess water loss, and other body matter particularly if you don’t perform resistance training to offset this muscle loss. The below quote from Anne Collins illustrates:

“When we lose weight we don't just lose fat. We lose a combination of body fat, and muscle tissue. For example, studies show that when we diet, the weight we lose is on average 75 percent fat and 25 percent muscle. Furthermore, a relatively high percentage of this weight loss is likely to be water loss. Remember, water accounts for about 70 percent of the total body weight of an average person, with muscle tissue containing roughly 75 percent water (plus 20 percent protein and 5 percent minerals), and body fat containing roughly 50 percent water.”

I can hear the chunky masses shrugging their well padded shoulders and saying “So what? Weight loss is weight loss.”

Wrong. The last thing any one needs is to lose muscle mass. Muscle mass IS the engine of your metabolism. The bigger the engine, the more fuel (fat and carbohydrates) is burned. Every pound of muscle lost equals less calories required every day.

Your goal should be to lose body fat and body fat ONLY.

Rob Maher wrote: "The equation to reduce body fat is simple: one must burn more calories than one consumes. Most diets try to do this with gimmicks by just reducing calorie intake, but it is easier to tip the equation if one also burns more calories. For a sedentary “average” female it is likely that only 1700 calories or so are needed to maintain the body each day. By increasing to a moderate activity level (e.g., walking several miles per week) the daily calorie requirement increases to perhaps 2000."

Okay, the laws of physics - which nobody has outwitted yet - requires the human body (with a normal metabolism) to burn 3500 calories in order to lose one pound of body fat. To lose 1 pound of fat in 7 days you'll have to create a deficit of 500 calories a day through diet and/or exercise. This means in order to burn 5 pounds of body fat in one week you'll have to create a calorie deficit of 2500 calories PER DAY. Losing 7, 10, 12 or more pounds of body fat – and just body fat alone - in a week is verging on the impossible.

Now, maybe eating a low carbohydrate / high protein diet will give you a metabolic edge and shift these numbers a bit, but it's not going to defy the laws of physics. If you're losing 5 pounds a week or more (and not working out hours and hours like an endurance athlete) you should be concerned and immediately start strictly tracking your body fat and lean mass ratios as well as looking at dehydration issues. Most gyms have bio-impedance body fat monitors and you can buy your own for around $75.

All this impatience and rush to see big number losses on the scale is not healthy or based on sound knowledge. There is nothing wrong with losing weight at a slow and reasonable pace. I lost 1/2 pound of body fat and gained 1/2 pound of muscle in the last ten days and I'm thrilled. But I busted my ass with an hour a day of weight training to stimulate muscle growth, and an hour a day or more of aerobics to burn calories, and ate a well balanced high protein diet moderate in fat and carbohydrates high enough in calories (above my BMR that's for sure) to allow muscle building..

Be forewarned, if you lose enough muscle through chronic dieting, lack of resistance training, and/or age related muscle loss and your metabolism becomes sluggish, you will end up having to consume very few calories just to maintain your weight. This is why some overweight dieters can maintain high weights on very little calories.

Low Carb Band-It recently wrote about her past experiences with low calorie dieting “I ate a lower calorie diet mostly, but I was eating less and less and I didn't want to get stuff metabolically where I couldn't eat only 800 calories a day to maintain my weight.

Just regular science says, when you weigh less you need less calories to run the body mass you have. I was already eating as low as 900 calories a day and not losing weight and I was 230lbs. It scared me to think of how little I would have to eat...eventually.”

As for adequate protein intake alone sparing muscle during very low carbohydrate diet, this seems to be attainable. A Nutrition and Metabolism article suggests this is possible in a controlled environment:

“Although more long-term studies are needed before a firm conclusion can be drawn, it appears, from most literature studied, that a VLCARB is, if anything, protective against muscle protein catabolism during energy restriction, provided that it contains adequate amounts of protein.”

While a low carbohydrate / high protein approach can prevent this lowered metabolism quandary, if a dieter drops the overall calories too low for too long adequate protein alone may not protect muscle mass or metabolism.

“Very Low Calorie Diets leading to deficiencies of certain essential amino acids and potassium were thought to have caused a loss of lean muscle mass, weakening of heart muscle, and heart irregularities which probably contributed to the death of at least 60 people in the United States. Such liquid protein diets are no longer generally available.”

This begs the question, if laymen with no medical or nutritional supervision are experimenting with various very low calorie diets, be they low carbohydrate and/or low fat, what are the chances adequate protein intake, let alone adequate levels of other nutrients, will be achieved?

One overlooked problem with reliance on ketosis is hunger is dampened. Without hunger you’re just guessing at how much protein or other nutrients your body needs. Hunger is an intuitive signal from your body that’s recently been bastardized by crappy foods that screw with your body chemistry. Many people never experience true hunger because food is so plentiful.

If you’re not getting your minimum daily requirement of protein your body will break down skeletal muscle and later organ muscle. (US RDA recommends 0.8 grams of protein per kilogram of ideal body weight per day for sedentary people. Active people and athletes require 0.9 grams and bodybuilders generally view 1.0 grams of protein per pound of body weight as a bare minimum).

A 200 pound man of six feet two with approximately 15 percent body fat (considered in the fit range) will have about 30 pounds of body fat. This leaves 170 pounds of lean mass including muscle bone, organs, etc. Maybe 125 or so of this is muscle if he’s an average Joe who doesn’t body build. If this man goes on a 1500 calorie diet (and at 15 percent body fat this diet seems unnecessary unless he’s an elite athlete looking to compete at single digit body fat percent) and eats a ratio of 40 percent protein, 50 percent fat, 10 percent carbohydrates, he’s eating 600 calories (150 grams) of protein a day. That being a little less than 1 gram of protein for each pound of body weight, it seems like he'd avoid muscle loss.

Now let’s look at a 170 pound woman around 5’ 7” with a history of yo yo dieting and minimal exercise. (Based on a 67 inch female with a 37 inch waist and 43 inch hips is 55% Body fat. Recommended BF% for this woman is 22%).

This gives her approximately 90 pounds of body fat and 80 pounds of lean mass. If she adopts a VLCD of 500 calories a day and eats a ratio of 40 percent protein, 40 percent fat and 10 percent carbohydrates her protein intake is 200 calories (75 grams of protein). Again this “appears” to be enough protein to prevent muscle loss.

BUT WAIT! Both people are eating less calories than their BMR (basal or resting metabolic rate) of 1980 for him and 1522 for her.

What happens when we eat less calories than our BMR?

While a negative calorie balance is essential to lose body fat this still is based on a number above your BMR unless you’re on complete bed rest. Eating adequate protein alone may not prevent muscle loss in the face of very low CALORIE dieting.

From Shape Fit:

“It is well known that cutting calories too much slows down the metabolic rate, decreases thyroid output and causes loss of lean mass, so the question is how much of a deficit do you need? There definitely seems to be a specific cutoff or threshold where further reductions in calories will have detrimental effects. The most common guideline for calorie deficits for fat loss is to reduce your calories by at least 500, but not more than 1000 below your maintenance level. For some, especially lighter people, 1000 calories may be too much of a deficit. The American College of Sports Medicine (ACSM) recommends that calorie levels never drop below 1200 calories per day for women or 1800 per day for men. Even these calorie levels are extremely low.”

So, what’s wrong with adopting a sensible diet and exercise plan that supplies enough calories and nutrients to stay healthy and active while cutting just enough calories to nudge your body into losing body fat slowly? Why the impatience and rush to see an unreasonably low drop on the scale every week? And why is there so much denial surrounding the detriments of muscle loss and other negative effects of extreme dieting? Why chase after a quick fix that really isn’t a long term solution you can live with?

Um?

Bottom line, I'm not here to judge what anyone chooses to do, nor am I here to condone behaviors I believe are of dubious value or dangerous. My goal is to share what has worked for me and others on our quest for health and fitness. But if my sibling, spouse, child, or friend asked what I thought about them going on a VLCD without medical supervision, I say DON'T. There are safer, healthier and more sustainable ways to lose fat and reach your goals.

Also check out these links if you’re interested in more information:


The Dangers of Low Calorie (under 1500) Diets

Very Low Calorie Diet Information

Metabolic Response To Starvation

The Fast Supper
Is a life lived on the edge of starvation worth living? Our hungry reporter gives the ultra-extreme Calorie Restriction Diet a two-month taste test

Fad Diets.com

Why You Want To Preserve and Build Muscle

Note that some morbidly obese people can lose weight more rapidly – particularly after WLS – because of their sheer excess of body fat and the early stages after surgery require a low calorie liquid diet. This does not mean losing five or ten pounds a week is healthy for moderately overweight dieters. It is likely that people with excess body fat who start a low carbohydrate or low calorie diet will lose weight rapidly in the beginning simply because the body is shocked into dropping large amounts of weight (and not just body fat). But it’s not healthy to sustain large weekly weight losses long term.