Weight Loss Manegement

Low-carbohydrate diets became a major weight loss and health maintenance trend during the late 1990s and early 2000s. While their popularity has waned recently from its peak, they still remain popular. This diet trend has stirred major controversies in the medical and nutritional sciences communities and, as yet, there is not a general consensus on their efficacy or safety.

As of 2008 the majority of the medical community remains generally opposed to these diets for long term health although there has been a recent softening of this opposition by some organizations.

This article summarizes a sampling of the studies and other research that exist related to this diet trend including not only the efficacy of these diets on weight loss, but also their effects on other aspects of health and related topics such as ketosis. This is not a complete listing of all relevant research.

Synopsis

Because of the substantial controversy regarding low-carbohydrate diets, and even disagreements in interpreting the results of specific studies, it is currently difficult to objectively summarize the research in a way that reflects scientific consensus.

Although there has been some research done throughout the twentieth century, most directly relevant scientific studies have occurred in the 1990s and early 2000s and, as such, are relatively new and the results are still debated in the medical community.[16] Supporters and opponents of low-carbohydrate diets frequently cite many articles (some times the same articles) as supporting their positions. One of the fundamental criticisms of those who advocate the low-carbohydrate diets has been the lack of long-term studies evaluating their health risks. This has begun to change as longer term studies are emerging.


Specific Research

The following is not a complete list of all relevant research but a selected list of articles demonstrating some of the breadth of scientific knowledge available on this subject.


Journal of the American Medical Association: 1926

Lieb et al., 1926 conducted a case study of Dr. Vilhjalmur Stefansson, an anthropologist and explorer who lived with the Inuit eating a diet consisting almost entirely of meat, fish, and fat. A research team studied Stefansson's health looking for signs that his "unusual" diet had adversely affected his health. The team was unable to find any health problems in Stefansson and noted that the Inuit themselves also were quite healthy.


Journal of Biological Chemistry: 1929

Tolstoi, 1929 performed a one-year study of two men who consumed a diet of exclusively meat. One of the subjects demonstrated a dramatic increase in cholesterol levels while the other actually lowered his cholesterol levels by the end of the study. All other health indicators were normal for both subjects.

Note that because of the magnitude of the reported increase (and decrease following the test period) in the cholesterol levels, the measurement methodology has to be questioned by modern standards (i.e. the numbers may not directly correlate to modern cholesterol measurement techniques).


The Lancet: 1956

Kekwick and Pawan, 1956 conducted a study of subjects consuming 1000-calorie diets, some 90% protein, some 90% fat, and some 90% carbohydrates. Those on the high fat diet lost the most, the high protein dieters lost somewhat less, and the high carbohydrate dieters actually gained weight on average.

Kekwick and Pawan noted irregularities in their study (patients not fully complying with the parameters of the study). As such the validity of the conclusions has to be questioned.


Annals of Internal Medicine: 1965

A study conducted in 1965 at the Naval Hospital Oakland (Oakland, California) used a diet of 1000 calories per day, high in fat and limiting carbohydrates to 10 grams (40 calories) daily. Over a ten-day period, subjects on this diet lost more body fat than did a group who fasted completely (Benoit et. al. 1965). Some advocates, such as Atkins, of low-carbohydrate diets have termed this the metabolic advantage of such diets.


Journal of the American Dietetic Association: 1980

Larosa, 1980 followed 24 patients for 12 weeks, 8 weeks on a high-protein, low-carbohydrate diet, studying their weight loss and cholesterol changes. The authors concluded the following.

The high-protein, low-carbohydrate dieting resulted in substantial weight loss ... Significant increases occurred in LDL-cholesterol, uric acid, and free fatty acid levels. HDL-cholesterol levels failed to rise despite significant weight loss ...
Despite weight loss the study found serious negative metabolic changes.


American Journal of Clinical Nutrition: 1997

Holt et al., 1997 performed a study of glucose and insulin responses for test subjects to a variety of foods, both high- and low-carbohydrate. The conclusions state the following.

Our study was undertaken to test the hypothesis that the postprandial insulin response was not necessarily proportional to the blood glucose response and that nutrients other than carbohydrate influence the overall level of insulinemia ... The results of this study confirm and also challenge some of our basic assumptions about the relation between food intake and insulinemia. Within each food group, there was a wide range of insulin responses, despite similarities in nutrient composition ... As observed in previous studies, consumption of protein or fat with carbohydrate increases insulin secretion compared with the insulinogenic effect of these nutrients alone (22, 30-32) ... However, some protein and fat-rich foods (eggs, beef, fish, lentils, cheese, cake, and doughnuts) induced as much insulin secretion as did some carbohydrate-rich foods (eg, beef was equal to brown rice and fish was equal to grain bread).
This study challenges the general assertion that only carbohydrates significantly impact insulin production.

The authors describe their work as "preliminary" and so the results should be judged with caution.