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.

Factors That Affect Speed of Weight Loss

The human body does not lose weight at a regular or uniform speed. Different people reduce weight at different speeds. This is because weight reduction is dependent on various factors, including: weight; diet and lifestyle; level of physical activity; health and genes (inc. metabolic rate); the level of stress experienced.

Weight Loss is Not an Exact Science

As you can see, not only does weight loss include other things besides fat-tissue, the actual speed of weight reduction is determined by a variety of individual factors. So it’s difficult, if not impossible, to give a precise answer to the question “how fast can I lose weight?” However, as a rough guide, here are some basic guidelines for maximum weight loss.

What is the Most Weight You Can Lose?

It is possible to lose anything up to about 20 pounds of weight per week, but most of this is likely to be water. It will therefore be regained as soon as normal eating resumes.

What is the Most Fat You Can Lose?

The maximum amount of body fat a healthy person can lose is about 3-4 pounds per week. Typically, only obese people are likely to be able to lose this amount of fat. By comparison, a woman of average weight (about 140 pounds) is likely to lose a maximum of about 1-1.5 pounds per week.

Why You Can’t Lose More Weight

The human body is not designed to shed weight. It is designed to survive! Our basic body chemistry endures from prehistoric times, when famine, rather than obesity, was the biggest threat. This is why it won’t lose excessive amounts of fat in a short period of time. In fact, if you drastically reduce your calorie-intake, your brain takes active steps to slow down your metabolism, in order to conserve calories. This is one reason why we encounter a weight loss plateau.

Side Effects of Losing Weight Too Quickly

Too rapid weight loss (eg. after bariatric surgery) can lead to unpleasant side effects. The two most common effects of over-rapid weight reduction include:

Appearance of Loose Skin

If you reduce weight too quickly, your skin does not have time to shrink to your leaner body shape. The only effective treatment for this is surgical intervention, such as Abdominoplasty (tummy tuck).

Gallstones

Studies have shown that people who lose excessive amounts of weight very quickly, have a greater risk of developing gallstones than those who lose weight at slower speeds. Too rapid weight reduction may also cause “silent” gallstones to become active.

Weight Regain (Weight Rebound)

Sudden fast weight reduction is usually caused by artificial changes to our eating habits as a result of (eg) very-low-calorie diet plans, or bariatric surgery. Not surprisingly, this does not give us enough time to learn new eating habits. So although our physical weight may have changed, our mental approach to food and eating remains the same. In the absence of medical supervision, or other support, we commonly find ourselves unable to sustain the new dietary habits required to maintain our lighter weight, and regain all our lost weight.