It is no wonder why the weight-loss industry is a $20 billion per year industry. Dieters spend money on diet books, diet drugs and weight-loss surgery. 108 million people in the United States are on diets and typically attempt four or five diets a year. 85% of dieters are women.
Some diets preach low-calorie, some are low-carbohydrate. Some allow for only eating grapefruit or cabbage soup. Some say it’s only about how much you eat and the amount of time spent exercising, while others say not all calories are created equal and it is about what we eat as well as how much of it. We are constantly bombarded by different information and different diets. No wonder we cannot keep the weight off.
A promising study published in the Journal of the American Medical Association may finally set the record straight. It found that a specific mix of carbohydrate, fat and protein might be ideal. It also suggested that not all calories are created equal, meaning that calories can have different effects on the body.
The study followed 21 adults ages 18 through 40 for four years to determine the effects of various diets on the ability to burn calories following weight loss. At the start of the study, the participants had a BMI over 27, which is considered overweight or obese. The participants were originally placed on a diet to lose 10%-15% of their body weight. After the initial weight loss, researchers placed the participants on three different diets in a random order each for four weeks at a time. All diets maintained the same total number of calories. However, they did differ in their carbohydrate, fat and protein content.
The low-fat diet required that 60% of calories came from carbohydrates, 20% from fat and 20% from protein. The low-glycemic diet required that 40% of calories be derived from carbohydrates, 40% from fat and 20% from protein in order to prevent spikes in blood sugar. The very low-carbohydrate diet (“Atkins”) required that 10% of calories came from carbohydrate, 60% from fat and 30% from protein.
Researchers measured participants’ energy expenditure as well as other aspects of metabolism and concluded that the total number of calories burned daily differed with each diet. Researchers also studied hormone levels and metabolic measures concluding that they too varied by diet.
On average the very-low carbohydrate diet burned calories most efficiently with participants burning 3,137 calories daily. The low-glycemic diet burned 2,937 calories per day, 200 less than the very-low carbohydrate. The low-fat diet burned 2,812 calories daily.
While researchers did conclude that it improved metabolism the best, don’t switch to the very-low carbohydrate diet just yet. The participants showed higher levels of risk factors for diabetes and heart disease, including the stress hormone cortisol.
The low-glycemic diet resulted in only a 200 calorie difference and showed similar benefits to the very-low carbohydrate diet, with less negative effects. A low-glycemic diet consists of less-processed grains, vegetables and legumes. According to researchers, this may be the best diet for both long-term weight loss and heart disease prevention when coupled with exercise.
A low-glycemic index diet emphasizes foods based on how they affect blood sugar levels. Foods, specifically carbohydrates since they have the most effect on blood sugar, are given a score between 0 and 100. High scores of 70 and up include white and brown rice, white bread, white skinless baked potato, boiled red potatoes and watermelon. Medium scores between 56-69 include sweet corn, bananas, raw pineapple, raisins and some ice creams. Examples of low scoring foods of 55 and under include raw carrots, peanuts, raw apple, grapefruit, peas, skim milk, kidney beans and lentils.
The diet does not require counting carbs, counting calories or reducing portion sizes. It only directs dieters to the right kind of carbohydrates in order to keep blood sugar levels balanced. Specifically, lower glycemic diets are digested less rapidly by the body, which raises the blood sugar in a regulated, balanced way; whereas higher glycemic foods and beverages are digested more rapidly causing a blood sugar spike followed by a drastic decline. Since low-glycemic index foods are digested more slowly, they remain in the digestive tract longer, potentially controlling appetite and hunger. This can also reduce the risk of insulin resistance.
The study shows that a low-glycemic diet can work for long-term weight-loss, as it is easily sustainable because whole food groups are not removed. Furthermore, it may reduce the risk of serious diseases such as diabetes and cardiovascular disease.
Sources:
Weight-Loss Stats: http://abcnews.go.com/Health/100-million-dieters-20-billion-weight-loss-industry/story?id=16297197#.UBBfZo7p7ao
NIH: http://www.nih.gov/researchmatters/july2012/07162012weight.htm
Mayo Clinic on the Low-Glycemic Diet: http://www.mayoclinic.com/health/glycemic-index-diet/MY00770