Low Carbohydrate Diets and Low Fat Diets

Recently I have been re-studying low carbohydrate diets spurred on by an extensive email dialogue with Dr. Richard Feinman, Prof. of Cell Biology at Downstate Medical School in Brooklyn (my alma mater), and by multiple inquiries about the Paleo diet from friends and acquaintances. Dr. Feinman is a highly-regarded scientist who has done research on metabolism in low carb diets and I have learned a lot from him. He studies and advocates a VLCKD (very low carb diet-20% of total calories from carbs with no fat restriction.) This is the diet that most lab research has been done on. It produces ketosis and ketone bodies supply much of nutritional needs of the cells rather than glucose. Dietary ketosis, as opposed to diabetic ketosis, is not harmful to the body. The source of the limited amount of carbs is optional but most advocates including Dr. Feinman eat leafy green and other non-starchy vegetables for their nutrient value and fiber.

Most low-fat and other low-carb diets recommend consumption of non-starchy vegetables and most fruits while avoiding sugars, refined grains and limiting salt. Some low carb programs suggest avoiding saturated fat as much as possible.

Vegetables and fruits can rarely supply enough calories for long-term existence in humans. Remaining calories have to come from either starches or animal products or refined vegetable oils.

Low-carb advocates suggest meat (some including Paleo want this to be low fat), fish, vegetable oils, and dairy products (Paleo excludes dairy and others say low fat dairy.)

Most low-fat advocates suggest starches.

Inside each camp there is variation with some low-carb people favoring organ meats and full fat dairy while others suggest no dairy at all. Many in the low-fat group aim at total fat consumption of 10% of calories and total protein consumption about the same. This is not the "low" fat diet of the AHA, ADA, Framingham Study, or Nurses Health Initiative Study which suggest 30% of calories from fat. But again there is variation, particularly in regard to the amount of seeds and nuts consumed. This group also advocates little or no vegetable oils except as found naturally in whole foods.

Books and articles on the subject have mainly been quite well written and sometimes very thoroughly researched. Low-carb supporters emphasize the need for insulin control as a basis for good health while low-fat advocates want to avoid almost all dietary fat especially saturated fat and cholesterol. There is excellent laboratory and clinical support for both these positions. Each of the writers from both groups tend to ignore the strong positions of the others while showing the rationale and clinical evidence for their position. I've not found a book or article which looks at it well from both sides. Some have termed this the war of the diets and I don't think that term is far off based on the approaches many scientists and authors have staked.

Another group of diets looks more towards portion control while supporting high vegetable and fruit intake with avoidance of sugar, refined grains and saturated fat. Variations on this theme were the most popular with professional nutritionists as seen in the 2013 "US News and World Report" evaluation of 29 diet programs by a panel of 21 nutrition experts selected by the magazine. In this survey, most of the low-fat diet programs were in the middle of the ratings and most of the low carbohydrate programs were at the bottom with the Paleo diet tied for last. Objections to both the low-fat and low-carb diets often centered around palatability and ease of adherence to the diet with the low-carb diets also criticized as not having long-term performance experience and a danger for development of vascular disease. My observation on these rating criteria is that many, if not most, people have a serious problem with portion control and keeping track of what quantity of food is eaten while they can more readily adapt to relatively unlimited quantities of certain foods while avoiding other foods entirely. Both the low-fat and low-carb diets typically offer this approach which many people I have talked to find easier. Also, results of these moderation diets are poor in the treatment of chronic disease. They may help somewhat in prevention but effects are small compared to a true plant based whole food diet.
Two popular versions of a lower fat, higher nutrient diets do not stress portion control. The Mediterranean Diet advocates lots of fruits, vegetables and fish plus oils with less meat, dairy, refined carbs. Compared to the standard American diet (SAD) people who eat this way live longer and have better health but do not have nearly the longevity or lack of chronic disease which those who eat a whole food plant based diet enjoy. This diet is not very effective in the treatment of chronic disease. Another version of a low-fat diet is flexitarian, in which the low-fat plant based whole food diet is modified to include small amounts of fish, low fat dairy and/or meat. Several knowledgeable physicians I've met follow this diet as preventative but say they would eliminate all animal products for themselves or patients to treat many chronic diseases. The issue for advocates of the low-fat diet is what qualifies as a "small" amount and how reliable patients will be if allowed this flexibility. Esselstyn says that he knows he can successfully treat all his patients with coronary disease so why take a chance on a modification.

Low-carb programs have convincingly shown excellent control of weight and metabolic syndrome (MetS) including diabetes and high blood pressure. Low-fat programs have had similar results with a comparison study between the two-favoring low-carb. However, in this study in the low-fat group 24% of calories came from fat which does not come close to the guidelines suggested by the low-fat diet promoters. Low-carb diets may also induce good serum lipid profiles which suggests to some researchers that atherosclerosis would be well treated and controlled by this diet. This diet also generates low blood insulin levels together with a ketotic state both favoring less cancer development and growth. Another hormone, IGF-1, a strong promotor of cancer growth, is increased with animal, not vegetable, protein consumption. I don't know how these changes balance out for tumor growth. I have not seen a study which treats patients with advanced coronary artery disease with a low-carb diet nor am I aware of any long-term studies in groups of patients following this program except those of contemporary indigenous groups in whom heart attacks are rare until western food choices are introduced. The few autopsy studies pre-western food in these people usually show atherosclerosis but they often die young for other reasons so that clinically relevant vascular disease and cancer rates are uncertain.

Low-fat diet programs are well documented to prevent and reverse advanced coronary artery disease and population studies of large groups following this diet show low rates of cancer and other chronic diseases especially vascular disease. This diet typically is associated with longevity and low end-of-life morbidity where there is not famine or infectious disease.
Many people have asked me about body building and diet. Most body builders and professional athletes eat large amounts of animal protein and many take protein supplements, usually but not always from animal products. I am convinced that any protein supplement, animal or vegetable is a bad idea. Isolated protein concentrates promote cancer growth according to many studies. Some world class athletes eat plant based diets and feel they perform better because of it (Venus and Serena Williams, Martina Navratilova, Arian Foster, Tony Gonzalez among others) and a few champion body builders also eat a plant based diet. However, I'm sure it is easier to build muscle bulk with animal products. A plant based diet may be as good or better for performance.
It is certain that you are very unlikely to have good health with lots of processed food, sugars, salt, and refined carbs in your diet and that if you combine a high carb with a high fat diet that you will have a poor diet likely to lead to chronic diseases. The question is; are some people better off with low carb and others with low fat. Certainly, some people strongly prefer one over the other. Is this genetic or due to degree of fat addiction or due to an individual's body doing better on one of them? Is it cultural? Does it matter which you choose? I am confident that you will thrive on a plant based whole food diet which avoids processed oils. A few people have reported doing poorly on this diet, then feeling better switching to a low carb diet or some modification of a fully plant based diet. When physicians have evaluated the few, who don't thrive typically they find a deficiency in vitamin B-12, an essential fatty acid, or a mineral (often zinc or iodine.) These deficiencies are easily treated. Constipation and headaches are usually a problem with low-carb diets but this is not the case with low fat (8-12%) diets. Incidence of vascular disease and cancer are certainly much lower on a low-fat diet. I don't know what they would be on a long term low carb diet.