by Joye
Willcox, Ph.D., R.D., LDN
The good news is that more people these days are aware of the health problems associated with being overweight and are trying to lose excess pounds. The not so good news is that a majority of those trying to lose weight are going the low carbohydrate route. When followed short term, this approach is not harmful for most folks, but long term can be a different matter. Additionally, short-term strategies at weight loss normally do not result in long term positive results, i.e. permanent weight loss.
First, let’s talk about short term consequences of the low carb, high protein diet. Most low carb dieters are very pleased with the immediate benefits of 1) being able to eat a lot of high fat foods that are normally restricted on weight loss diets and 2) a significant drop in pounds on the scale. Unrestricted fat intake can be fun and satisfying, but let’s face it, the laws of cardiac physiology have not been rewritten. Saturated fats are still atherogenic, in other words they do promote the process of atherosclerosis. A healthier moderately high fat intake, in the range of 30-35% of total calories would provide adequate satiety for most people. The important point is the type of fat consumed. Polyunsaturated and unsaturated fats (canola oil, olive oil based dressings and sauces for example) are healthy dietary fats as opposed to saturated fats found in cheese, fatty meats, etc. which are often selected by low carb dieters.
Another point is that low carb promoters did not rewrite the laws of metabolism.
Weight loss is a very simple formula: calories in (food) versus calories out (activity). The higher fat and protein approach promotes satiety (feeling satisfied longer) after a meal because fat and protein leave the stomach after carbohydrate. That is why most weight management professionals including registered dietitians, recommend a fat intake that is appropriate for the individual, i.e., not so high that the calories are out of range, but also not so low that the individual is always hungry! One point that is sometimes lost when people follow either the low carb or low fat dietary approach is that total calories determine weight loss. Foods low in fat or low in carbohydrate are not necessarily low in calories.
One point to the whole low carb approach that deserves further discussion is the fact that carbohydrates are not created equal. This is one truly positive effect of the low carb trend. People are becoming more aware of the “empty calories” added to food in the form of sucrose, high fructose corn syrups, and other sweeteners. Many lower carb alternatives with or without artificial sweeteners are now available in many food products. Clearly, choosing complex over simple carbohydrates is a healthier choice due to fiber content as well as phytochemicals, bioflavonoids, and other substances that may reduce the risks of many chronic diseases. Several studies have confirmed that diets high in fruits and vegetables, and whole grains are associated with reduced risks of cardiovascular disease, obesity, and some forms of cancer.
The low carb approach can be unhealthy long term because the body must break down protein and fat to provide the majority of energy that normally comes from carbohydrates. Basically, the liver has to take nitrogen from protein to convert it to a carbohydrate for energy. This build up of nitrogen is toxic and must be excreted. So the kidneys kick into action and start excreting the nitrogen by-products urea and ammonia, and in doing so cause an increased loss of body water. This can lead to dehydration and electrolyte imbalances. Increased levels of uric acid from high protein intake can also lead to increased risk for gout. Further loss of total body water occurs as stored glucose (glycogen) levels are depleted. Incidentally, this loss of body water often accounts for a significant amount of body “weight” lost during the initial phases of low carb dieting.
As large amounts of fats from the diet are used for energy, ketones are produced which also lead to diuresis and dehydration. In general, a more acidic environment is established when protein and fat are the primary energy sources. The body tries to neutralize this acidic environment by pulling on stored bases. The major base storage in our body is calcium from bones. Therefore, increased bone loss leading to osteoporosis may be a long term risk of following the low carb diets.
The popular low carb diets also tend to restrict the intake of fruits, vegetables, breads, and dairy. These food groups provide important nutrients that provide essential functions and additional protection as antioxidants. Dairy servings provide calcium, which has been shown to promote healthy body fat loss.
The bottom line is simple. Body fat is lost when there is an energy deficit, i.e., when more calories are used than are consumed. This deficit should be in the range of about 500-750 calories a day which translates to a fat loss of 1 to 1.5 lbs. per week. Remember, this means 52-78 lbs. per year! Creating a larger energy deficit than this will tend to decrease the resting metabolic rate, which is a counterproductive process. A wiser choice would be to create this energy deficit while maintaining the quality of one’s diet.
Planning for a diet intake that is well balanced between the food groups will insure that more of the essential nutrients are available. A well balanced mildly energy deficient diet, coupled with an effective exercise program, can be followed long term until a healthy weight is attained. At this point, energy intake can be increased for maintenance needs.
Achieving and maintaining a healthy weight is one of the most important things an individual can do to promote good health. But, taking it a step further, losing the weight while making healthy food choices is the best approach!
Joye Willcox, Ph.D., R.D., LDN Healthy Diets, Inc. www.healthydietsinc.com
