Calorie restriction is an important part of any weight loss plan, but crash diets that rely on the elimination of virtually all calories and carbohydrates can restrict the diet to the point that the body misses out on a lot of important nutrients. That can change the way that the body functions, often resulting in side-effects beyond the intended weight loss.
How the Body Deals with Low Calorie Intake
The whole point of calorie restrictive diets is to make sure that the body does not take in enough calories to function, forcing it to burn the calories that it has stored in the form of adipose tissue. This is what can drive weight loss while following a calorie restrictive diet.
Many of these diets are high in protein because protein sources, especially animal-derived protein sources, are very low in carbohydrates, which the body breaks down into energy. The body can also break down proteins as a source of energy. Because calorie restriction can trigger a survival mechanism in the body that causes it to stop burning calories, the body usually starts breaking down proteins first. When proteins are broken down by the body they release acids into the body, lowering the body’s pH leading to a state called “Ketosis.” Ketosis, often a symptom used to diagnose illnesses and disorders, is often seen as a good sign by crash dieters.
Because proteins are a very inefficient source of energy, the body will usually not break down large volumes of it for long before beginning to burn fat as a primary source instead. The body usually continues to break down proteins, leading to prolonged ketosis, which can cause bad breath. Too low a pH for too long can also lead to damage of the organs that filter blood, namely the liver and kidneys.
When Avoiding Sugars Means Avoiding Vitamins and Minerals
Many calorie restrictive diets heavily limit the amount of fruit and vegetables that a person can eat because these foods are often high in natural sugars, which are a source of calories. Fruits and vegetables are also sources of vitamins, minerals, antioxidants.
Minerals help the body both directly, and by being synthesized into other structures. Minerals are best known for being incorporated into bones, which is an important part of the body, but they are also required for the formation of blood cells and muscle fibers. Fortunately there is a good amount of iron in red meats, so this shouldn’t be a problem for most crash dieters.
Similarly, cheeses usually have virtually no carbs, but is high in calcium. If all you’re eating is meat and cheese you are likely to have other problems going on, but more on that later.
Vitamins help the body perform most of its functions from immune response to vision and many other roles. While some vitamins will be present in meat, provided the animal it came from had a healthy diet, most vitamins in the average diet come from colorful fruits and vegetables.
Vegetables tend to have significantly less sugar than fruits, so any carbs and calories still allowed to dieters on calorie restrictive plans should try to fill that space with a variety of vegetables.
Carbs Should not be Cut at the Expense of Fiber
One of the most carbohydrate-heavy food groups is grains, which makes breads and pastas the bane of many dieters, which is unfortunate because these foods are also fairly high in fiber, especially if those breads and pastas are made with whole grains.
Probably the most important role of fiber – strings of carbohydrates that the body cannot break apart and digest – is helping to move other foods through the digestive tract, especially the lower digestive tract. A diet high in animal products and by-products but low in plant products is usually very low in fiber, which can lead to foods moving very slowly through the digestive tract. This can lead to digestive disorders like constipation and gas, as well as an upset stomach and bad breath.
Vegetables like broccoli are low in carbs and calories, but high in fiber, so crash dieters should be sure to eat as many vegetables as their diet plan allows. Beans also have fairly high fiber, as well as some iron, though they are more notably another protein source.
Too Much Protein and Iron?
Calorie restricted diets often lead to a deficit of many important nutrients, but usually result in an abundance of protein, and sometimes iron. Eating more protein can help build muscle, but only if the body was not getting enough protein before. There is a large misconception that increased protein consumption directly leads to muscle growth, but the body does not store excess protein in the muscles the way that it stores excess calories in fat. If a person consumes more protein than they actively use it simply goes to waste. It should also be noted that most people tend to get more protein than they need already, so a diet that is significantly higher in protein is not likely to do the muscles any good.
Iron, however, cannot be broken down, and is not so easily passed from the system as excess protein. This can lead to excess iron circulating in the blood where it can damage internal organs, notably the liver and the heart.
Ways to reduce excess iron include reducing it in the diet by eating less red meat, and more chicken, and fish. Iron can also be sequestered in the muscles by working out more, especially anaerobic exercises like weight lifting. A last ditch effort for removing extra iron is donating blood, as iron accumulates in red blood cells. The body can make red blood cells, though it can’t make iron, so the red blood cells that the body produces to replace those donated will have a lower iron content.
Severely calorie-restricting diets can lead to drastic weight loss over a fairly short period of time, but should only be followed for a short period of time to increase mobility, or even drop a few sizes before an important event. Following them too closely for too long can lead to a number of complications due to the large variety of foods that they forbid.