Weight loss is, without a doubt, the most common fitness goal. It is also one of the most frustratingly difficult to achieve. A basic understanding of the mechanics of weight loss (and weight gain) and its contributing factors might help to demystify this most fundamental step towards fitness.
In its simplest form, weight loss is a result of a caloric deficient. Which is a fancy way of saying that you are burning more calories than you are eating. So the best way to lose weight quickly is obviously just to eat very little, right? To an extent but, as always, the body is much more complicated than that. These complicated little details are the downfall of a particularly insidious form of diet called the "crash diet."
Crash diets are extreme and restrictive and generally ignore proper nutrition altogether. They are intended for rapid weight loss over a short period of time and, if used, should not be maintained longer than instructed. Here's a quote from Crash-Diets.com, an online guide and supporter of crash diets: "If you undergo any crash diet longer than it is intended, you may encounter health problems as it restricts certain essential nutrients needed by the body."
Note that those nutrients being restricted are "essential." They are necessary and vitally important and your intake of them should not be tampered with.
So what's the problem? There are two issues that crash diets tend to overlook which make them an unfavorable solution: Sustainability and basic nutrition.
Sustainability
Calories are the fuel of your body. Even if you were just laying around in bed all day, most people would burn somewhere around 2000 calories just breathing, pumping blood and all the other things we don't think about that keep us alive.
This exact number, referred to as your Basal Metabolic Rate, is different for everyone and can be calculated pretty accurately with this handy little tool here.
Crash diets generally require caloric intake to be lower than your BMR and, in some cases, even lower than 1,000 calories per day. Remember, these numbers don't take into account any physical activity. You can't put half a tank of gas in your car and expect it to go as far as it does on a full tank.
Just like a car that's running out of gas, your body will begin to slow down when on an extremely restrictive diet. If you drop your caloric intake too low, about 1200 according to most dieticians, your body will start to panic and go into starvation mode. Your metabolism slows and you will actually stop losing weight. You may even start to gain it back.
Any weight lost using a crash diet, is not likely to stay lost.
Basic Nutrition
There are six basic nutrients that are necessary to the body. These are water, protein, fats, carbohydrates, vitamins and minerals. Each of these substances performs a unique and essential function in the body and must be present in sufficient quantities to get its job done.
Carbohydrates and fat are the basic sources of calories and are constantly being broken down to their raw caloric value and subsequently burned for fuel. Carbohydrates and fat also tend to be the most commonly vilified nutrients and are excluded from most crash diets.
A major problem is that, as mentioned previously, these extremely low calorie diets actually slow down your metabolism. The best way to speed up your metabolism is regular aerobic exercise which can't be done without a proper balance of carbohydrates, fat and protein. So now the dieter's muscles aren't being strengthened through exercise but they are being cannibalized by the body to compensate for the fuel it isn't receiving through diet.
Crash diets will absolutely help you lose weight. But the weight is more than likely to return quickly and you are going to be unhealthy throughout the course of the diet. The best solution is still the good ol' fashion balanced diet and exercise. Here's a good article about how to lose weight quickly and safely while exercising from the fine folks over at WebMD.
