Must Carbohydrates Be Eliminated for Weight Loss?

Does the argument ever end? Which is the best diet, the easiest, the one with the quickest results, the latest? Anyone who has attempted to follow one or many weight-loss regimens over the past several decades is familiar with diets that promise lasting and immediate weight loss (without hunger, of course) only to find that the diets didn’t work for them, and certainly did not keep weight off permanently. And when the diet becomes a major source of income for its proponents because of foods manufactured just for that particular weight-loss regimen, oftentimes the marketing can be more persuasive than the results.

Such is the case now with the familiar keto diet. Supermarkets and pharmacies are filled with products that can be consumed on a diet that restricts or eliminates foods containing any carbohydrates. The premise of the keto diet: When the body switches away from glucose (the end product of carbohydrate digestion) for energy and uses fatty acids for energy in its place, the fat cells empty out and the body becomes slim. The diet is promoted as natural and metabolically desirable, despite that the body is programmed to use glucose, not fat, for energy.

One advantage, however, of a diet that forbids most or all carbohydrates is the removal of temptation. For most, it is hard to resist the temptation presented by chocolate, cookies, cakes, pies, doughnuts, chips, ice cream, and freshly baked bread slathered with butter. These carbohydrates are full of fat and sugar and can be densely caloric. Eliminating the possibility of eating them, if one can so manage, means that a major source of unwanted calories is immediately eliminated from daily food intake. Of course, any diet will try to persuade the dieter not to eat these foods by making them totally forbidden, because if consumed they will interfere with ketosis, making the argument so much more compelling.

Unfortunately, eliminating most carbohydrates leads to eliminating a vast number of non-sweet, non-fat carbohydrate foods that are good sources of fiber and nutrients. It is difficult to obtain fiber from protein and fat, the mainstays of a keto diet. Mayonnaise slathered on an omelet, a meal a woman was consuming at a table near us recently, meets the requirements of a keto diet but may leave her intestinal tract yearning for fiber. Conversely, many carbohydrates are high in fiber. Beans, lentils, oatmeal, whole-grain breads, corn on the cob, baked white or sweet potatoes, apples, and quinoa are just a few examples of carbs that are high in fiber. Vitamin intake may also be limited or indeed absent on a carbohydrate-free diet and scurvy, a serious Vitamin C deficiency disease, has been reported for individuals who avoid all carbohydrates.

Fortunately, high-fiber supplements such as Metamucil and vitamin-mineral supplements are available to compensate for the absence of adequate amounts of fiber and nutrients on a strict ketogenic diet. But this should not be the only reason to accept or reject this way of eating to lose weight. The obvious argument for or against a diet that eliminates so many foods humans are accustomed to eating should be the diet’s success in long-term weight loss.

Fortunately, there is data to aid in making this decision. A recent publication reviewed the results of 61 studies comparing the weight loss of almost 7,000 adults who followed diets of varying carbohydrate content. The authors analyzed the weight loss obtained on three types of diets:

1. Very low carbohydrate or ketogenic diets containing less than 50 grams of carbohydrate a day
2. Low carbohydrate diet containing 50-150 grams of carbohydrate per day
3. Balanced carbohydrate diet containing 150 + grams of carbohydrate a day

The diets lasted between three and eight and a half months. There was [minimally?] greater weight loss on the low and very low-carbohydrate diets; dieters lost on average about a kilogram more weight (2.2 pounds over several months) than those who followed a balanced protein-carbohydrate food plan.

However, it should be noted that when carbohydrate intake is greatly reduced, the body loses water, perhaps one to three pounds worth. This is because it takes a certain amount of water to store carbohydrates, and when those stores are used up on a low-carb diet, the water leaves the body. As soon as carbohydrates are eaten, the water returns along with a water-based weight gain of a couple of pounds.

The results of this scientific review may not alter which weight-loss program a dieter chooses to follow. However, it does provide enough information so that the choice is not based on claims or promises that are not substantiated by the results of many studies. The claim, for example, that carbohydrate causes weight gain, and a high-fat diet promotes substantial weight loss has to be evaluated in light of this extensive review.

Eliminating sugary, fatty carbohydrates makes nutritional sense for people of all weights. So too does eliminating high-fat, high-cholesterol foods as a dietary staple. The dieter is left with is a predictable, even boring weight-loss regimen that meets nutritional needs and produces a slow, predictable weight loss. Such a diet may not make an interesting conversation among one’s friends, but neither does a conversation about using dental floss or taking a daily walk. However, such a diet allows the dieter to move effortlessly into a sensible, healthy way of eating for the rest of his or her life. And since longevity may in part be based on what we eat, that outcome is worth a boring diet.