Americans spend billions of dollars on weight-loss products and programs every year. Despite this, most people do not lose the amount they would like or, if they do, regain the weight after a short period of time. The problem lies with following specific fads that emphasize one type of eating pattern. The low-carbohydrate diet, which has been popular off-and-on-again since the mid-1800s, exemplifies such a diet program. Studies do show that the low-carbohydrate diet can offer some benefits, but over the long-term does not offer any more advantages than any other diet. Other factors, such as adherence to the diet and lifestyle are more important to the equation.
Americans spent approximately $60 billion in 2009 on weight loss products and programs, including so-called "special" diet foods, appetite suppressants, diet books, exercise memberships, workout videos, and stomach-clamping surgery (World Health Organization, 2010). Yet obesity, especially among children and youth, continues to climb. Statistics find that normally one-third of the female population is on a calorically restrictive diet at any one time. About 30% of girls have already been on a calorically restrictive diet by the time they reach the teenage years with more than 70% of girls having been on one by the time they attend college after high school graduation. Further, over the past two decades, there have been scores of new diet books. Regardless, in most diets people either do not lose much weight, or as much as they wanted, or gain the pounds back in a short period of time. Many of these diets result in temporary weight loss, which comes as no surprise since the person is eating less, but the long-term success rate is typically less than 5%: More than 95% of individuals undergoing caloric restriction return to, or above, their pre-diet weight within five years, most within two-year, whether it is a low carbohydrate or any other form of diet (lecture material from class). They have spent considerable time and money on weight loss programs and products that may work in the short-term, if that. Presently, the main approach to weight loss is through a host of different forms of calorically reduction diets, including low-carbohydrate intake; the majority of these fads have little empirical basis or substantiation. Research does find repeatedly to consistently lose weight for the long-term it is necessary to decrease caloric input and increase activity at the same time. A diet, such as the low-carbohydrate, will not work on its own for the long-term.
This report will review academic studies that have been conducted within recent years to support the thesis that diet alone, in this case the low-carbohydrate diet, cannot help a person lose weight for the long-term. It will provide a concluding overview of the literature review and any additional studies that would be recommended.
The low-carbohydrate diet has a history that stems back to the mid-1860s. In 1862, a London undertaker, William Banting, was so obese at 5'5" and 202 pounds, that his fat was pressing on his inner ear and he could not hear. His doctor put him on a starch- and sugar-free diet; he was only allowed meat, fish, and vegetables. In 1890, Wilbur Atwater, an agricultural chemist, discovered the calorimeter and measured the amount of heat food produced. This unit of measurement was named a calorie. The body, burned calories; if a person ate more than what was burned, he or she would gain weight; the opposite would occur when more was burned than eaten. In the 1940s, a researcher, Dr. Alfred Pennington, theorized that people became fat not because they were eating too much, but because of what their bodies did with certain foods -- it turned what they ate into fat. He said people were not losing weight with a low-calorie diet, because this did not eliminate the fat; overweight people do not fully break down the carbohydrates and most are therefore converted to fat. When people were placed on a high-fat, high-protein, low-carbohydrate unrestricted-calorie diet, they felt well, enjoyed their meals and were no longer hungry between meals. Twenty obese individuals being treated lost an average of 22 pounds each in about three-and-a-half months (Sawyer & Gale, 2008). The diet became a fad, worked for some people and then disappeared when the newest weight-loss method appeared. This low-carbohydrate concept arose again with Dr. Robert Atkins New Diet Revolution in 1992. This diet continues to be popular under a number of different names despite contradictory results.
A wide number of studies have been conducted in recent years to specifically look at the results of the low-carbohydrate diet. A study was conducted by Miller et al. (2000) followed 18 Atkins dieters for a month. Throughout the first two-week period, the dieters consumed 1,419 calories a day, compared with 2,481 calories a day before starting the diet. They lost an average of about eight pounds. During the next phase, these dieters averaged 1,500 calories daily and shed another three pounds in two weeks. The participants in both phases significantly reduced carbohydrates, over 90%, but the actual amounts of fat and protein consumed changed slightly. Adherence to the diet did not appear positive. Some patients felt tired, and others were nauseated on the plan. Most said they were eager to return to their earlier dietary habits. The results of another study (Hellmich, 2000) found that the 41 overweight participants adhering to the Atkins diet for half a year lost an average of 10% of their initial body weight. Most of these dieters reduced their blood cholesterol level by 5%, but some increased their cholesterol levels and. Half of the subjects followed the program for a year and maintained their weight loss. The analysts of the National Weight Control Registry studied the diets of 2,681 members who maintained at least a 30-pound weight loss for a year or more. The authors thought that the number of adherents to the Atkins diet would be significantly represented in this number of individuals who maintained their weight loss. However, only 1% of these successful dieters followed a diet where there was less than 24% of their daily calories from carbohydrates. Looking at the adherence rate it was concluded: In the low-carbohydrate group, the mean duration of successful weight maintenance was 19 months; for those who consumed greater than 24% of calories as carbohydrates, the mean duration for weight retention was 36 months. The researchers concluded that the Atkins diet may not create the favorable "metabolic advantage" as was claimed.
Studies such as these on low-carbohydrate diets concluded: 1) No type of diet is good for everyone; 2) the best type of diet may be determined by heredity factors; 3) because carbohydrates can raise triglyceride levels, a low-carbohydrate might be good for obese individuals with abnormally high triglyceride levels; 4) carbohydrates, especially foods made up of simple carbohydrates, can also be related to low HDL levels. Some research has found that a low-carbohydrate diet can raise the HDL level; low-carbohydrate diets are not advisable for people with such illnesses as coronary artery disease, gout, or kidney disease.
There are also studies that compare two or more diet approaches, particularly with the low-carbohydrate diet, to determine if one is better than another in both weight loss and healthcare benefits derived. Foster et al. (2003), researchers at the University of Pennsylvania, reported the results of a controlled study of 63 people who were randomly assigned to either the Atkins low-carbohydrate diet or a conventional one. The low-carbohydrate group lost about 4%
more weight for the first six months, but there was no significant difference between two groups at one year. The low-carbohydrate diet also seemed to improve the risks of heart disease, but the researchers agreed that additional studies were required for the safety and effectiveness of this dietary approach. In 2005, Dansinger et al. compared the Atkins, Ornish, Weight Watchers and Zone Diets to determine which was better, if any, for weight loss and risk of heart disease: The Atkins diet necessitates minimal carbohydrate intake without fat restriction; the Zone diet modulates macronutrient balance and glycemic load; the Omish diet restricts fat; and the Weight Watchers is a well-rounded dietary approach, but needs to meet specific guidelines. The authors were also interested in seeing if a difference existed in adherence to the diets. A randomized trial was conducted with 160 overweight or obese adults aged 22 to72 with known hypertension, dysplidemia or fasting hyperglycemia. The diet study went for two years. After two months of maximum effort, participants selected their own levels of dietary adherence.
The authors (Dansinger et al., 2005) found that each popular diet modestly reduced body weight and several cardiac risk factors for the first year. Yet they also found that this was true only for the minority of people who continued a high dietary adherence level; overall, adherence and cardiac care was shown to be more important than the specific diet and cardiac care. In this study, none of these diets produced a better adherence rate, but…