Let’s begin by defining the word “diet.” A “diet” is any severe restriction of food or calories that’s temporary. Most conventional diet programs call for extremely low calories: 800-1200 or less for women and 1500-1800 or less for men. Any time you restrict calories drastically like this, you will lose weight. So if your only criteria for success is weight loss, and you don’t care where the weight comes from, or how long it  stays off, then you could say that “all diets work.” There are two major problems with this approach: First, the weight loss from very low calorie dieting almost never lasts; 95% of the people who lose weight on conventional diet programs can’t keep it off. The second problem is that most of the weight you lose from low calorie dieting is muscle, not fat. If permanent fat loss without  losing muscle is your goal (it should be), then it would be closer to the truth to say “diets never work.”

Statistics prove that diets never work in the long term. If they did work, then howdo you explain the huge obesity problem today? And why is it getting worse? According to the National Institute of Health, there are over 100 million overweight people in theUnited States. That’s 55% of the adult population! Over 20% of U.S. adults areclinically obese, which means they are at risk for one or more of over 30 health problemsthat are associated with excess body fat.

If you eat more calories than you burn, you will store the excess as body fat. Ifyou eat fewer calories than you burn, you will lose fat. Simple mathematics, right? Well,not exactly.If fat loss were as black and white as calories in vs. calories out, then how do youexplain why some overweight people eat less than lean people, yet they still can’t lose anounce? And how is it possible for someone with a 2200-calorie maintenance level to eatonly 800 to 1000 calories a day without losing any weight?Using the strictly mathematical model, if you cut out 1000 calories per day fromyour maintenance level, that will add up to a 7000-calorie deficit in one week. There are3500 calories in a pound of stored body fat, so cutting out 1000 calories a day should – in theory – produce a weight loss of two pounds per week. Actual real world fat loss rarelyworks out with such mathematical precision. Rob Faigin, writing in the book “Natural Hormonal Enhancement,” makes a humorous, but true observation about calorie balance and weight loss. Faigin says, “If there existed an airtight mathematical relationship between caloric intake and weight loss,cutting caloric intake from 3000 to 1000 would result in a 60,000 calorie per year deficit – and would result in a 200 pound weight loss after a year. What if the person began thediet weighing 200 pounds, would he disappear?”

When a calorie deficit is first introduced, weight loss generally occurs rapidly, justas the numbers would dictate, but it never takes long before weight loss slows, and theneventually stops completely. Why does this happen? Why is it that you don’t lose 50pounds in 25 weeks or 100 pounds in 50 weeks with a 1000-calorie deficit?The explanation is quite simple: Over thousands of years, humans havedeveloped a weight-regulating mechanism that recognizes when there’s a food shortageand decreases energy expenditure to “protect you.” This survival mechanism is known asthe “starvation response.”

You can survive for months without food. You’ve probably heard stories aboutpeople getting lost in the mountains or wilderness for months with no food at all (onlywater), or being confined in a prisoner of war camp for years with only tiny amounts offood. What makes surviving under these conditions possible is your body’s remarkableability to slow down its rate of calorie burning. When your body senses calorie deprivation it says to itself, “It looks like this is allthe food we’re going to be getting for a while, so we’d better stop burning so manycalories and start saving our energy. This way we’ll be able to survive longer on the little amount of food we have.”The starvation response developed largely from exposure to adverseenvironmental conditions like droughts, natural disasters and food shortages.Furthermore, there were no supermarkets ten thousand years ago - if people wanted to eat,they had to either grow their food or kill it. It’s likely that at times, ancient man didn’tknow when the next meal was coming and may have only eaten once or twice a week. The starvation response evolved in humans to ensure the survival of the species.

This wonderful feature of human evolution is a blessing if you’re stranded out inthe wilderness with no food. During periods of starvation, the body slowly begins to feedoff itself, burning fat stores, muscle and even internal organs for energy. If you continuedto burn calories at your normal rate, your limited reserves of stored energy would beexhausted quickly and you would die very soon after you food supply was cut off. Thestarvation response keeps you alive longer.

Unfortunately, this same life-preserving mechanism can work against you whenyou’re trying to lose weight because your body can’t tell the difference between dietingand starvation!Severe calorie cutting always sends your body into “starvation mode.” There’s nothing you can do to stop this from happening other than to avoid severe calorieshortages!

The consequences of low calorie dieting are automatic and unavoidable. Theresponses are metabolic, hormonal, and psychological in nature, and include: Decreasedmetabolism, loss of muscle, increased activity of fat-storing enzymes and hormones,decreased activity of fat-burning enzymes and hormones, decreased thyroid output,increased appetite, increased chance of regaining weight, and decreased energy and workcapacity. Let’s take a quick look at each.