Nutrition

What Are The Differences Between Low-Carb Diets? Do They Provide Lasting Weight Loss?

What Are The Differences Between Low-Carb Diets? Do They Provide Lasting Weight Loss?

According to the Centers for Disease Control (2012),1 overweight and obesity in America have reached epidemic proportions:  in 2009-2010, 35% of U.S. men and women were obese.  This number had risen since 1999-2000 from 27.5%.  The main reason why so many Americans are currently overweight or obese is because of decreased activity and poor diet.  The diet portion of this spectrum is much more difficult to master for the population.

The carbohydrate controversy is one reason why Americans remain confused about what to eat.  Is a low carb diet better than a low fat diet? Better than Weight Watchers? A review of the literature suggests that low-carb diets are not better than balanced diets for weight loss or weight maintenance.


How Do Carbohydrates Provide Energy?

low carb dietsBefore we can understand how carbohydrates can play a role in weight loss, gain and maintenance, we must first know exactly what a carbohydrate is.  Carbohydrates are the body’s prime source for energy.

Carbohydrates are stored in the liver and the muscles as a substance called glycogen.  When carbohydrates are ingested, the body breaks those particles down into glucose and this glucose is then transformed into glycogen.  When we exercise, this glycogen is the first energy source used until those stores in the liver and muscle are depleted, or used up.  Once the glycogen stores are all used up, the body still requires energy.  This energy is going to come from our fat stores, which will generate weight loss.  Carbohydrates supply 4 kilocalories (calories) per gram (100g= 400cal).


Simple & Complex Carbs

Carbohydrates may be broken down into complex and simple carbs.  Complex carbohydrates are those that are slowly digested and do not spike insulin rapidly, giving a constant feeling of fullness.  Examples of complex carbohydrates are oats, brown rice, whole grains, vegetables, and some fruits.  These types of carbohydrates should be consumed in higher amounts because that feeling of fullness, also known as satiety, will make a person feel fuller longer and will in turn help the person not eat more than he or she needs.

On the other end of the spectrum there are simple carbohydrates.  Simple carbohydrates are almost exclusively made of glucose, fructose, or lactose, which are simple sugars.  These types of foods digest very quickly and should be consumed in lesser amounts by the individual.  Some examples of simple carbohydrates are candy, most fruits, white rice, and white bread.  These foods spike the body’s insulin very quickly and do not have the same satiety (fullness) effects as complex carbohydrates. For weight loss, a persons diet should be focused around complex carbohydrates with simple carbohydrates only being consumed after exercise bouts.  This is because the body’s glycogen stores are depleted and simple carbohydrates of glucose will quickly replenish these needs.


Is Carbohydrate Management Key In Weight Management?

The reason why carbs are so directly involved in storing energy (in the form of fat), carbohydrate management has often been seen a key to weight management. Various “fad” diets have been suggested to control weight by controlling carb intake. The two most popular low carbohydrate diets that we will look at are the Atkins Diet and the South Beach Diet.  Throughout the rest of this paper, we will discuss multiple studies that have been conducted regarding these two diets.

The Atkins Diet

Dr. Robert Atkins created the Atkins Diet in 1972. The Atkins diet is recognized by its concept of cutting calories from carbohydrates primarily. Studies of the Atkins diet suggest that it poses problems both with the consumption of fats and of proteins.

The Atkins Diet does not put a limit on the amount of fats that can be consumed, which can lead to an increase in the dieter’s risk of heart disease.  In a study conducted by the University of Kentucky, 6professionals analyzed sample menus of food eaten by subjects over the course of the week while on the Atkins Diet.  They revealed that the diet consisted of 59% fat and that there was a significant decrease in consumption of grains, vegetables, and fruits as recommended by the U.S. Dietary Guidelines.  They also stated that although there may be short-term weight loss, there was a greater chance of increasing the risk of cardiovascular disease and cancer in the long-term.

low carb diets

Another study conducted by the Bassett Research Institute in Cooperstown, New York,  followed a group of Atkins dieters for a month while on the plan.  The dieters had reduced their caloric intake (to 1500 cals) by about 40% than before they started the diet (2500 cals).  Although the participants lost an average of 8 pounds in the initial two weeks and then an average of 3 pounds in the last two weeks, the diet cut back on carbohydrates by more than 90%.  This cutting of carbohydrates (main source of energy) left the patients feeling tired and, at times, nauseated.  Most of the dieters said that they were eager to get back to their previous diet.  This shows that the drastic cutting of carbohydrates as a form of energy can interfere with daily life and the likelihood of quitting the diet before completion is high.

Where Does Your Energy Come From On The Atkins Diet?

Diets that eliminate carbohydrates require nutrition from other sources, mainly from proteins and fats.  The risks of high consumption of fat are well known, but the risks of the high consumption of protein are less so, leading the nutrition committee of the American Heart Association to issue a science advisory warning the health risks of consuming a diet that is extremely high in protein.  These experts concluded that diets that promote high protein and high fat might produce short-term weight loss through dehydration, but that the high fat content may be harmful to the cardiovascular system over time, and a very high- protein diet can be very risky for patients who suffer from diabetes because it can speed the progression of diabetic kidney disease.  This is because proteins are filtered through the kidneys, and when there is excess, it puts a lot of pressure on the kidneys and they can break down.

One last study in 2007, conducted by Christopher Gardner, 10who is the assistant professor of medicine at the Stanford Prevention Research Center, concluded that the Atkins Diet was superior when it came to comparing weight loss on other diets.  He wrote that, “health professionals have either dismissed the value of very low-carbohydrate diets for weight loss or have been very skeptical of them, but it seems to be a viable alternative for dieters.”  He followed dieters over the course of one year and concluded that the people assigned to the Atkins Diet lost almost two times as much weight as those on other diets.  Other noted changes included decrease in body mass index, triglycerides, and blood pressure.  Gardner believes that the Atkins diet was successful in this group because of the simplicity of the diet.  He stated that it is very straightforward in telling you to eliminate processed carbohydrates to lose weight, which targets the issue found in most Americans diets right now.  There are some downfalls to this study though that should be noted.  The same Atkins dieters that led in pounds lost had also gained more weight back than those following the other diets tested.  Gardner also cautioned that the Atkins diet could lead to long-term health problems that would have arisen after the 12-month testing period.  Gardner concluded that while the Atkins diet is the top choice for people who want to lose weight in the short term, it could be particularly difficult to maintain the weight loss.

In all of the studies reviewed, there seems to be a common conclusion.  The Atkins diet can produce some weight loss and a reduction of heart disease risks in the short-term, but it has not yet been determined if this diet is safe for the long-term.  These low-carbohydrate diets have made food companies to produce “low-carb” foods.  These foods are generally higher in fat and processed additives than the foods that they replace.  Experts believe that this advertising of “low-carb” foods leads people to think that they are eating healthier, when in reality they are eating foods that are really not healthy.  Not everybody is going to see the same results, so seeking proper supervision from a physician is highly recommended.

The South Beach Diet

The other low-carbohydrate diet that has been popular recently is the South Beach Diet, which was introduced in 2003 by cardiologist Arthur Agatston and which has not been widely studied.  We will begin by focusing on what makes the South Beach Diet different and sometimes preferred over the Atkins Diet.

The South Beach Diet, is sometimes called a modified low-carbohydrate diet and is structured around a meal plan that is lower in carbohydrates and higher in proteins and healthy fats than a typical diet.  The key word there is “healthy” fats.  This is one of the first differences between the two diets.   The South Beach Diet claims that it keeps its meals nutrient dense with good carbs, lean protein, healthy fats, and fiber that makes it easy to follow for a lifetime.  The diet also helps educate the dieter on what foods are healthy vs. not healthy, such as what are bad carbs and why they are bad and what fats should be eaten in moderation vs. those in higher amounts.

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Another difference between the South Beach Diet and the Atkins Diet is that the South Beach Diet is not necessarily a true low-carbohydrate diet.  A normal eating plan, 11 will consist of about 45-65% (225 to 325 g on a 2000 calorie diet) carbohydrates, the South Beach Diet will consist of around 28% (140 g/day) carbohydrates, and a true low-carb diet will consist of about 50-100 g of carbs per day.  When it comes to exercise, the South Beach diet recommends getting regular exercise as this will boost your metabolism and help prevent weight-loss plateaus and keep weight loss constant.

Another thing that differentiates the two diets is that the South Beach Diet is split up into multiple phases (1,2,and 3).  So, there is an elimination of bad foods phase, a long-term weight loss phase, and then a maintenance phase.  Phase 3 (maintenance) does not start until the dieter’s goal weight has been reached.  According to the South Beach Diet experts, dieters lost between 8 to 13 pounds in the two-week phase 1 period and that during phase 2, you can expect to lose 1 to 2 pounds per week (which is the recommended rate).

Key Comparison Studies

One key study looked at the results of weight loss, improved blood lipid levels and improved waist-to-hip ratio over the course of 12 weeks.  The two diets were one called the National Cholesterol Education Program (NCEP) diet, which replaced saturated fat with carbohydrates or one that replaced saturated fat with protein and monounsaturated fat called the isocaloric modified low-carbohydrate (MLC) diet.  The MLC diet is lower in carbohydrates but higher in protein, monounsaturated fat and complex carbohydrates. The results of this study were that the MLC diet caused significantly greater weight loss over the 12 weeks compared to the NCEP diet.  Weight loss was the primary goal.  There were no significant differences between the blood lipid levels or waist-to-hip ratios.

Another key study looked at the effects of a modified carbohydrate diet (MCD) on the bodyweight and fat in overweight and obese men and women. Kraft Foods tested 87 subjects between the ages of 18 to 65.  The subjects were randomly assigned either a MCD diet or a low-fat, portion-controlled diet (control group).  The participants on the MCD diet were instructed to consume low-carbohydrates (40g/day) during the first 2 weeks and then introduce low glycemic carbohydrates back into their diets for weeks 2-12.  The control group was instructed to reduce fat and decrease portion sizes and aim to be in a caloric deficit of 500-800 kcal/day.  It was not indicated if exercise was done during the course of this 12 weeks.  At the end of the 12 weeks study, the results showed that the MCD diet provided greater weight loss and fat loss and also showed improvements in serum triglycerides and total/HDL cholesterol ratio compared to the control group.


Do Low-Carb Diets Provide Long-Term Weight Loss?

Now that we know just what goes into a low-carbohydrate and the differences between a few of them, are low-carbohydrates really beneficial for lasting weight loss?  The results have shown that if your goal is short-term weight loss, then yes, low-carbohydrates diets can be successful.  But, it can become unhealthy to be on low-carbohydrates for an extended period of time and weight gain often comes with stopping the diet.  Some experts believe that it is not the reduction of carbohydrates that makes you lose the weight, but the fact that you replace those carbs with proteins and fats that make you feel fuller for longer.

The Atkins Diet claims that their eating plans will improve serious health conditions, such as diabetes, high blood pressure, and heart disease, but the truth is that any diet that helps a person lose excess weight can reduce or even reverse these risks.  Some low-carb diets restrict carbs so much that nutritional deficiencies can result. A lot of Americans buy into new fads and diets that guarantee weight loss when the real reality of it is to consume the right nutrients, stay active, and to be in a caloric deficit each day.  People do not need to starve themselves to lose weight.


Take-Home Message

The answer to the question of do low-carb diets promote lasting weight loss – the answer clearly is no.  For short-term weight loss they can be useful but in the long run, the health risks of continuing the diet long-term and the consequence of probable weight gain after stoppage should be the prime reason why people should find other ways of lasting weight loss.  Proper diet, exercise, hard work, and patience are a few of the best possible ways for keeping the weight off.

Dieting can be frustrating, but it can also be very rewarding.  If you are patient, healthy, and don’t lose sight of your goal, then there is no doubt that you will eventually achieve it.


David Rynecki B.S., M.S., CPT, FNS, CES, CSS, Pn1

Sports, Fitness, and Rehab Specialist

Tel: 717-491-2204

Email: dmrynecki@gmail.com

Facebook: https://www.facebook.com/DavidRyneckisFitnessPage

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