There are hundreds, if not thousands, of weight loss diets on the market, but they all work in one of two ways:
- By restricting the amount of calories in your diet to the point where you consume fewer calories than your body needs for weight maintenance.
- Be severely restricting your carbohydrate intake, so you enter a state of ketosis and your body starts burning fat for fuel instead of glucose.
Low Calorie Diets
The vast majority of weight loss diets–including many low carbohydrate diets–fall into this category. Low calorie diets are based on a simple principle: When you eat more calories than you need, you gain weight, and when you eat less calories than you need, you lose weight. Most of the popular low calorie diets provide in the neighborhood of 1000 to 1400 calories a day. Diets providing less than 1000 calories a day are generally considered crash diets, and are almost always a bad idea. Not only is it very difficult to stick to an extremely low calorie diet for longer than a week, but if you do manage to stick it out, such diets can lower your metabolic rate to the point where you start gaining weight on half the calories you needed for maintenance prior to embarking on the crash diet.
Many low calorie diets are upfront about the fact that they work by restricting your calorie intake, but some would have you believe that it’s their special combination of foods or some other gimmick that results in weight loss. With the exception of extremely low carbohydrate diets that induce a state of ketosis, such claims are hogwash. There are no special food combinations that facilitate weight loss.
Of course some foods are better for your health, and avoiding certain foods or food combinations can help some people reduce cravings, but you lose weight by consuming less calories than your body needs. Purely from a weight loss perspective, it really doesn’t matter what those calories consist of. You could eat a thousand calories worth of Snickers bars a day and you would still lose weight.
Overt calorie counting is not always necessary for a low calorie diet to work. Some low calorie diets emphasize portion control without calorie counting. This is often combined with lists of allowed/forbidden foods or required food combinations to ensure that anyone following the diet eats low calorie meals. Low calorie diets pretending to be based on a principle other than reduced calorie intake sometimes claim you can eat all you want. While they may indeed allow you to have all the raw vegetables you can eat, they give themselves away by limiting your consumption of high calorie items such as nuts. In the end, it always comes down to calories.
Low Carb Diets
When the Atkins diet was published in the early 1970s, it was promoted as an “eat all the high fat foods you want, and still lose weight” diet. As long as dieters restricted their carbohydrate intake to less than 20 grams a day, they could dine on all the steak, lobster smothered with butter, pork ribs, and scrambled eggs they wanted. How was this possible?
Extremely low carbohydrate diets such as Atkins are termed ketogenic diets because they work by putting your body in a state of ketosis. Instead of burning glucose for energy as is the case on a diet that does not restrict carbohydrate intake, your body burns its own fat stores for fuel. When the fat is metabolized, ketones are released into your bloodstream. Ketones supply energy to the brain and, to a lesser extent, the heart when blood glucose levels are low. They are excreted in your breath (this is why “bad breath” is a typical side effect of ketogenic diets) and your urine (low carb dieters often use urine testing strips to check whether they’re in ketosis).
Not all low carb diets are ketogenic diets. In most people, ketosis is induced by restricting carbohydrate intake to less than 30 grams a day. Some low carb diets provide substantially more carbohydrates than that. Others, such as the South Beach Diet, include a brief ketogenic phase, after which you eat moderate amounts of “good carbs” (those would be complex carbohydrates with a low glycemic index), while continuing to avoid sugars and refined carbohydrates. Non-ketogenic low carb diets work by restricting calorie intake.
Ketogenic diets appear to produce very rapid weight loss, but most of the weight lost during the first couple of weeks is water. While this is true for all diets to some extent, ketogenic diets have a particularly pronounced diuretic effect, so it’s extra important to remain well hydrated and replenish water soluble vitamins and electrolytes.
Eventually your body will adapt to the altered metabolic state, and you will need to restrict your calorie intake to continue losing weight. Studies indicate, however, that people on ketogenic diets have a tendency to eat less calories anyway. The reasons for this are twofold. First, many people find that ketosis helps to curb both hunger and cravings. And second, the limited food choices make overeating far less likely.
While some medical professionals and nutritionists question the long-term safety of ketogenic diets, such diets need not be unhealthy as long as you focus on eating healthy fats (e.g., lots of omega-3 polyunsaturated fatty acids, less saturated fats), avoid/limit meats, eggs, and dairy products from animals pumped full of antibiotics and growth hormones, and use your carbohydrate allowance wisely, making sure to eat as many green vegetables as you can while remaining in ketosis. Unless you eat organ meats regularly, a vitamin/mineral supplement is also recommended.
Low Calorie or Low Carb: Which Is Right for You?
Since many low carb diets are also low calorie diets and even ketogenic diets eventually require calorie restriction if weight loss is to continue after adaption occurs, perhaps this question is more accurately phrased as: Is a low carb diet right for you?
There’s no question that low carb diets are hot right now to the point where many people regard carbohydrates as “bad” and synonymous with weight gain. But are they really? Not too long ago, fat was America’s dietary bogeyman. Everything non-fat was considered good, and fat made you fat. Many people failed to distinguish between healthy fats and unhealthy fats or moderate fat consumption and heavy fat consumption. All fat had to be avoided if you wanted to lose weight or be healthy.
Now we’re seeing the same pattern with carbohydrates. Some carbohydrates–like some fats–are indeed unhealthy and should be avoided or at least highly restricted: sugars and the heavily refined carbs found in many processed foods. But carbohydrates also include vegetables, fruit, whole grains, and legumes–foods chock full of antioxidants and phytonutrients proven to lower the risk of everything from heart disease to cancer. As for weight issues, let’s not forget that vegans, the group of Americans with the lowest obesity rate, tend to eat diets very high in (complex) carbohydrates.
For most people, there’s no need to drastically limit food choices by restricting carbohydrate intake. Even people who are sensitive to carbs with a high glycemic index do not usually find it necessary to eliminate almost all carbohydrates from their diet. On the other hand, we’re all individuals, and there’s no such thing as one diet that’s perfect for everyone. If your carbohydrate cravings are out of control or you have a medical condition that may respond to reduced carb levels, why not give a low carb diet a go and see if it helps.