Low carbohydrate diets can reduce weight while diets rich in vegetable protein and oils improve heart health. Combining both diets might also combine the benefits.
A recent study compared a low carb vegan diet with a high carb lacto-ovo vegetarian diet for their effects on weight loss and heart health. People on the low carb vegan diet did not eat any animal products, dairy or eggs. Those on the high carb lacto-ovo vegetarian diet were allowed low fat or skim dairy and egg substitutes.
At the end of six months, more weight loss was seen in the low carb group as well as a significant decrease in LDL cholesterol compared to the high carb group.
The study was conducted by David J. A. Jenkins from the Department of Nutritional Sciences, University of Toronto, Toronto, Canada and his team.
This study was a continuation of an earlier diet study. In that study, 47 people were given a metabolic diet for one month. In that diet, participants ate only 60 percent of their estimated caloric requirements each day. At the end of that diet study, the subjects were asked if they wanted to continue on another diet study for six months.
Twenty-nine people entered this diet study. They were divided into two groups — 19 were assigned to the control high carbohydrate lacto-ova vegetarian diet (high carb) and 10 were assigned to the low carbohydrate vegan diet (low carb).
The low carbohydrate vegan diet emphasized fiber, such as barley and oats, and low carb vegetables, such as eggplant and okra. No animal meat or products, including dairy, were allowed. Protein was provided by soy and nuts.
People on the high carb lacto-ovo vegetarian diet were allowed whole wheat cereals, liquid egg substitutes and low fat or skim dairy products.
The researchers measured body weight and blood levels of lipids, including low density lipoprotein (LDL) and cholesterol, blood sugar and blood pressure over the course of the research study.
Results of the research showed significant weight loss in the low carb group compared to the high carb group. The average weight loss in the low carb group was 15.2 pounds and 12.8 pounds in the high carb group. Significant decreases were also seen in LDL, cholesterol and triglycerides in the low carb group, compared to the high carb group.
Levels of blood glucose, insulin resistance and blood pressure were similar between both diet groups.
The research team calculated the effect of the changes in blood lipids on coronary heart disease. Compared to the high carb diet, the participants in the low carb group had a 2 percent calculated decrease in risk of coronary heart disease.
Half the people on the low carb diet dropped out or were withdrawn from the study, and 32 percent of those on the high carb diet left the study. Most of the reasons given had to do with being unavailable or too busy to be in the study. Three people had increases in their blood lipids and were withdrawn from the study by the researchers.
The authors of the research study cited the small number of people in the study and the high dropout rate as limitations of their research.
“We conclude that a weight loss which reduced carbohydrate in exchange for increased intakes of vegetable sources of protein, such as gluten, soy and nuts, together with vegetable oils offers an opportunity to improve both LDL cholesterol and body weight, both being risk factors for coronary heart diseases,” the authors wrote.
The research was published in the February issue of the BMJ.
Funding for the research was provided by Solae, LLC, Loblaw Companies Limited, and the Canada Research Chair Program of the Federal Government of Canada.
Dr. Jenkins disclosed numerous competing interests, including serving on advisory boards and/or receiving financial support from the Almond Council of California, the Canola Council of Canada, the International Tree Nut Council Nutrition Research and Education Foundation and the Peanut Institute, Kellogg’s and Quaker Oats.