Fad Diets: The Good, The Fad & The Ugly

by Leah Frankel, MS, RD | frankel@myhousecallmd.com

With a new diet making headlines each week it can be more than a little confusing deciding which diet will give you the results you’re looking for. Many of these diets have some good intentions but can be very stringent or not realistic to follow for more than a few days. Most fad diets cut out entire food groups, making it difficult to meet the nutrient requirements we need for our bodies to function properly. These fad diets become popular because people actually lose weight on them; many of these fad diets will reduce your caloric intake in one way or another leading to weight loss…it’s not rocket science. Last year, a nutrition professor lost weight on a diet consisting of twinkies and donuts because he simply decreased his overall calorie intake. We don’t recommend the Twinkie Diet (it is obviously lacking in several areas including fruits and vegetables), but it proves a valuable point: there’s more to a healthy diet than weight loss.  We’ll not only discuss the basic idea behind recent fad diets, but also get into the good, the bad and the ugly aspects of each.

Fun Fact: According to the Boston Medical Center, approximately 45 million people go on diets each year.

hCG Diet

The idea: hCG (human chorionic gonadotropin) is a hormone that is naturally produced during pregnancy, and it is the same hormone that many pregnancy tests are detecting to determine if you are pregnant. During pregnancy, hCG tells the hypothalamus (a part of the brain) to break down fat stores to provide nutrients for the developing placenta and fetus. The hCG diet combines daily injections of the hCG hormone with a 500 calorie/day diet.

The good: There is really nothing good we can say about this diet; injecting hormones and consuming only 500 calories/day is unsafe, period…and odd.

The bad: A severely restrictive diet, such as this 500-calorie diet, is rarely recommended unless you are being constantly monitored by medical staff (these types of diets are VERY uncommon even with medical supervision). When you only provide your body with 500 calories, it breaks down anything it can to get energy, this includes carbohydrate stores in your liver, muscle, and fat. Muscle helps keep your metabolism up, so by reducing your calories this severely you will actually end up slowing down your metabolism. Not exactly the ideal way to lose weight. In addition, restricting your calories to only 500 a day can make it extremely difficult to meet your recommended intake for most nutrients, including vitamins and minerals. The hCG hormone has been approved by the FDA for use as a fertility drug, however, it has not been approved for weight management or weight loss. In addition, research has not proven that hCG will provide any more weight loss than a calorie reducing diet alone (1). You need a prescription to take the regulated for of hCG thus the majority of people taking this hormone as part of this diet (notably without a prescription) are taking formulations that not regulated or approved by anyone.  Scary stuff.

South Beach Diet

The idea: The South Beach Diet is based on the principle that small portions of whole grains, lean protein, healthy fats, snacking, and appropriate portion sizes will aid in weight loss.  There are three phases of the diet. In the first phase, foods including fruit, pasta, bread, potatoes, alcohol, sweets, and certain starchy vegetables including carrots are eliminated. In the next phase, you can gradually add back some of the banned foods including carrots, tomatoes, onions, and small portions of fruit. Once you reach your goal weight, you begin the final stage where you can incorporate all of the banned foods while following some basic guidelines.

The good: In the final stage of the diet, reasonable portion sizes, fruits, vegetables, whole grains, and lean proteins are all emphasized. During this stage of the diet, when foods are reintroduced into your routine, no major food group is lacking. This focus on normal, healthy eating is a stark contrast from the logic behind most diets, which force you to limit foods or eliminate an entire food group for the rest of your life to stay lean.

The bad: As with any diet that limits carbohydrates, followers of the South Beach Diet will lose weight initially, primarily due to a loss of water weight. It is important to note that the loss of water weight can alter your electrolyte levels, causing dangerous side effects.  In addition, during the initial phase of the diet when carbohydrates are restricted, it is possible to develop a condition known as ketoacidosis.  When your body doesn’t have enough sugar to use for energy, fat is broken down instead. Ketoacidosis results from a buildup of ketones in the body during this breakdown process and can cause coma and even death.  In addition, restricting food groups like fruits and grains during the first phase of the diet may make it difficult to consume your daily requirement of minerals, vitamins, and fiber that you need from these foods.

Atkins Diet

The idea: The main idea behind the Atkins diet is to severely limit carbohydrates and replace them with high protein foods, forcing your body to breakdown fat instead of utilizing carbohydrates from food. Since fruits and most vegetables contain carbohydrates, these need to be eliminated as well. Many Americans eat excessive amount of refined carbohydrates and this diet reduces the consumption of these processed foods while also eliminating whole grain carbohydrates.

The good: Reducing our intake of processed foods, including chips, cookies, and ice cream would probably do us all some good. The diet recommends eating more frequently and encourages snacks throughout the day. Snacking throughout the day helps keep our appetite in check, preventing us from overeating at meals.

The bad: Carbohydrates are important for brain function and providing energy. A diet like the Atkins diet cuts out carbohydrates, including those from fruits and whole grains, which provide vital nutrients and fiber. Fiber not only prevents constipation, it also aids in lowering cholesterol levels in our blood. As we discussed earlier with the South Beach diet, people following the Atkins diet are at risk of developing ketoacidosis as well. The Atkins diet promotes consumption of protein-rich foods, regardless of fat content; therefore you are likely to increase your consumption of many high fat and high cholesterol foods including beef and cheese, increasing your risk of developing high cholesterol and heart disease. According to Atkins’ website, you can lose up to 15 lbs in 2 weeks. Sounds great, right?  Not exactly.  Weight loss of more than ½ to 2 lbs a week is unhealthy and unsustainable (2). Finally, as we discussed in our “Decoding Diets” article, low carbohydrate diets are no more effective than low fat diets; calories are the most important factor to consider when trying to lose weight.

Grapefruit Diet

The idea: The Grapefruit diet is arguably the one fad diet that has stood the test of time: it has been around since the 1930’s. While there are many versions of this diet, it is typically a 12 day program with an intended weight loss of 10 lbs. During the diet, grapefruit or grapefruit juice is eaten before each meal along with a limited variety of foods, including spinach, tomatoes, full fat salad dressings, coffee and 64 oz. of water, all while limiting calories to 800-1200 calories/day. You are only allowed to eat foods on the approved list and can only snack after dinner. Grapefruit is believed to accelerate fat burning and lead to weight loss.

The good: As with most fruits and vegetables, grapefruit does provide a number of nutrients including Vitamin C and fiber, and is relatively low in calories. In addition, eating grapefruit or grapefruit juice before a meal is a great way to add an additional serving of fruit to your diet. This diet also promotes the consumption of 64 oz of water; many people do not drink enough water and we can sometimes confuse the feelings of thirst and hunger so it is good that this diet promotes adequate hydration.

The bad: The Grapefruit diet not only restricts calorie levels but also reduces a number of food groups, making it difficult to meet daily requirements for a number of nutrients. Such a severe calorie restriction can also lead to some less-awesome effects including exhaustion, fatigue and headaches. While you will lose weight on such a restrictive diet, it will primarily be water weight and the weight will return once the 12-day diet ends. In addition, since there is little variety in the types of foods you can eat, you will likely give up on the diet quickly without developing many healthy eating habits. Finally, grapefruit interacts with a number of medications, so you need to be careful before eating grapefruits or drinking grapefruit juice if you take medications daily.

Blood Type Diet

The idea: With the Blood Type Diet, you follow a particular diet plan based on your blood type: A, B, AB or O. An individual with type A blood would follow a vegetarian diet, someone with type B blood could eat meat and dairy but no chicken, corn, or wheat, while type AB’s can eat some meat, but not cured meats, caffeine or alcohol, and an individual with type O blood can eat meat but no grains. In addition to diet recommendations, this diet also provides exercise tips based on blood type, such as intense physical activity for type O individuals and calming exercises for type A people.

The good: Many fad diets don’t include exercise regimens, so we applaud the Blood Type Diet for encouraging its followers to include physical activity in their approach to weight loss. While the tips vary based on blood type, there are some great recommendations including getting 8 hours of sleep, emphasizing the importance of not skipping meals, eating small meals every few hours, and eating while sitting at a table.

The bad: The first problem with this diet is that there is no scientific evidence that suggests this diet will work. We have yet to prove that people’s processing of foods and nutrients varies by blood type in any way, shape, or form.  Depending on the diet for your blood type, it can be difficult to meet your recommended intake of certain nutrients, particularly if an entire food group is eliminated. It can also be difficult to follow your particular diet if it interferes with any food allergies or intolerances, such as a lactose-intolerant person who is encouraged to eat dairy. Since each diet plan has such specific lists of foods to eat and avoid, it can be hard to follow this diet plan if it doesn’t match with your food preferences.

Master Cleanse Diet

The idea: This diet originally began in the 1940’s as a method to eliminate toxins throughout the body. There are several versions of this diet including the Lemonade diet and the Maple Syrup diet, but the idea behind each diet is to stop eating food and, instead, drink a particular concoction for 10 days or so. Typically, each day is started with a quart of water mixed with salt. Throughout the day you drink a mixture of fresh lemon juice, water, maple syrup and cayenne pepper. Finally, at the end of the day you drink an herbal tea laxative.

The good: The one good feature to this program is that it focuses on drinking fluid throughout the day. Many people do not drink enough water.  We can at least guarantee that people following the Master Cleanse will be drinking enough fluids. Depending on which version of the Master Cleanse Diet you follow, the diet typically continues for 10 days at which point you resume eating a regular diet for about 2 months before another round of detox. We are glad that this diet is not recommended for an extended period of time, but in now way endorse this plan (see below for “The bad”).

The bad: One of the biggest problems with this diet is that it doesn’t provide enough protein, fat, carbohydrates or minerals & vitamins for your body to function normally. Only drinking one type of beverage every day is enough to make you irritable.  Add in the fact that this concoction provides insufficient nutrients and you’re creating the perfect storm for headaches, lethargy, malaise, etc. You might be thinking that the idea of detoxifying your body sounds great and may be necessary to live a clean and healthy life; remember that our bodies have plenty of mechanisms for eliminating toxins without going on a cleansing fast. The liver is an unfaltering detoxifying machine that works around the clock to keep your body toxin-free.  It doesn’t need you to stop eating essential nutrients to help it along.  The last problem with this diet is the laxative. Taking laxatives on a regular basis can disrupt your normal GI tract as well as upset your electrolyte balance.  Electrolyte abnormalities are extremely dangerous and can lead to sudden death.  No bueno.


As you’ve seen, there are a lot of crazy diets out there.  While most of them can help you lose weight in the short term, you’ll be lacking some essential nutrients or cutting your calories a little too severely in the process. The goal is sustainable healthy eating.  The best way to lose weight is to eat a balance of foods from each food group including fruits, vegetables, healthy fats, lean protein, and whole grains! Watch your portion size and eat small, healthy meals throughout the day.  Remember that healthy eating should be a lifelong commitment, not a 10-day plan, so choose eating habits that you can stick to for the rest of your life.

Take Home Message: While fad diets may help you lose weight in the short term, many of these diets are lacking essential nutrients and are difficult to follow for the rest of your life. You’d be much better off choosing a well balanced diet containing foods from all of the food groups in appropriate portions.

What should you do when the next fad diet comes around?: The next time you hear about a new fad diet, apply the information you learned in this article to debunk the diet and understand why it might not be the best option despite it’s ability to help you lose weight.


  1. Stein MR, Julis RE, CC Peck, et all. Ineffectiveness of human chorionic gonadotrop in weight reduction: a double blind study. American Journal of Clinical Nutrition 1976; 29:940-948.
  2. www.atkins.com
  3. http://www.bmc.org/nutritionweight/services/weightmanagement.htm


02 2011

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