Why are certain fad diets bad for my health?

Lauren Harris-Pincus
Nutrition & Dietetics

By definition, a fad diet rises to popularity quickly and then fades. It usually is extremely calorie restrictive and eliminates one or more food groups. The fact is that fad diets are rarely based on sound scientific principles, and can actually make you sick. When these diets are written, they rarely address individuals with existing medical conditions. For example, a very high protein, low carb diet can be dangerous for a person with kidney disease or diabetes. A very high carb diet can also be detrimental for a diabetic, especially if the source of the carbohydrate is white, refined flour like bagels, pasta, white rice and white bread. Fad diets may help you lose weight quickly by dramatically decreasing your caloric intake and changing your eating habits. However, they are rarely a plan you can stick to, nor should you. Most people regain weight lost on fad diets and then some. Your best bet: stick to a weight loss plan that includes all food groups in the right portions. (Think  Stick to whole grains at each meal, along with fruits, vegetables, lean meats and fish, and nonfat or low-fat dairy. Don't forget the nuts and beans, they are packed with nutrition and are great accents to meals. Remember, when it comes to choosing a diet, if it sounds too good to be true, it probably is! 

Michaela Ballmann
Nutrition & Dietetics

Fad diets promise quick, easy weight loss, which gets many people to jump on the bandwagon. Unfortunately, this type of weight loss is unhealthy and very difficult to maintain. Here's why:

Weight loss is best when it is slow and steady. Losing about 1-2 pounds per week by decreasing one's Calories intake by 500-1000/day (or exercising more, or a combination of the two) is the best. It requires changes to your diet and lifestyle, but the changes can be small. You can take it at your own pace, learning to eat smaller portions and make healthier choices, and increase your physical activity. On the contrary, fad diets are a drastic shift and causes a lot of water loss and muscle loss (in addition to fat), that can often trigger yo-yo dieting and a regain of weight (maybe even higher than you were before).

Diets are a bad idea. The term diet, as it is commonly used, to describe a short-term fast or change of behavior from your norm, is a recipe for disaster. It promises unrealistic effects and makes you an emotional rollercoaster. Rather than eating mindfully and intuitively, listening to your body for cues on what and when to eat, you look to a book or some other external cue to make those decisions. In doing this, you lose contact with your body and its needs.

Fad diets restrict major macronutrients. The most popular fad diets are low in carbohydrates (think Atkins, Dukan), but there is always a significant restriction on the intake of healthy foods and nutrients that are important to maintain a healthy body. Let's take a low-carb diet for example. You have to limit your intake of fruit, starchy vegetables, grains (even whole/unrefined ones like quinoa, brown rice), etc. In doing so, you are missing out on the antioxidants, vitamins, and minerals found in these foods. When on a fad diet, you may need to take a multivitamin--another indicator of its inadequacy. 

To learn more about fad diets, listen to my podcast episode on this topic at:

Nadine Pazder
Nutrition & Dietetics

Fad diets by definition are a quick fix and not a long-term solution. While a safe rate of weight loss is 1-2 pounds/week, a fad diet may promise to have you lose 10 pounds in just one week. Any plan that causes a rapid weight loss is promoting the loss of water and some muscle, components that you need for health, strength and your body to function properly.

Some fad diets blame your extra weight on carbohydrates and direct you to severely limit them or avoid them altogether. Carbohydrates digest into a simple sugar called glucose, which just happens to be the preferred fuel for your muscles, nervous system, brain and the rest of your vital organs. Carbohydrates also contain vitamins, minerals, antioxidants and fiber to keep your body energized and functioning at its best. It is easy to develop vitamin deficiencies when you eliminate whole grains, fruits, vegetables and dairy from your diet.

Fad diets that limit your intake of carbohydrates tend to be high in protein and fat. While small amounts of protein in your meals can leave you feeling full and satisfied, larger intakes can make you dehydrated if you don't increase the amount of fluids that you drink.

Diets high in animal protein can also be high in saturated fat which over time can create blockages in the blood vessels leading to the heart leading to a heart attack.

Of course, this is all very simplified. But the risks are real and more significant if you already have a chronic disease like diabetes or high cholesterol. If intentional weight loss is in your future, make an appointment with a licensed registered dietitian to help you navigate choices and develop a plan tailored to you.

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
Fad diets come and go, and some can be downright unhealthy. Learn what you should eat to lose weight as Dr. Oz and dietitian Samantha Heller discuss fad diets in this video.

Karen Ansel
Nutrition & Dietetics

Even though they may seem different, most fad diets work the exact same way: they're low in calories. Often, to achieve such a low calorie level many of these diets cut out one of more food groups. Unfortunately, that can zap your energy and even have serious short and long-term consequences for your health.

Eating smaller portions of healthy foods is a much more enjoyable, healthy and effective way to slim down - and it's easier to maintain long term too.

Marjorie Nolan Cohn
Nutrition & Dietetics

Many fad diets are extreme and do not have a healthy balance of all the food groups. Fad diets may work to take the weight off but generally do not keep it off. If you want to lose weight, keep it off and not compromise your health a well balanced and calorie controlled diet combined with moderate amounts of activity is the way to go.

Sharon Palmer
Nutrition & Dietetics
Many fad diets, as far back as the grapefruit diet, are based on a diet concept that has little scientific support. That means that someone has written a book about an idea that they believe works, but there's really no proof that it will work for you. When an author of a fad diet shares glowing reports of personal stories or anecdotes regarding the diet, that's not the same as hard science. In addition, always be careful when a diet book advises you to cut out many foods, especially entire food groups. When you eliminate entire food groups, or cut your food choices down to a narrow few, you may be skipping out on important nutrients. Also, a diet should be a way of eating for life, not an impractical "diet" that you go "on" and "off" of. 
Jim White
Nutrition & Dietetics
Many fad diets take extreme measures that usually involve cutting out one or more food groups. The calorie intake that they allow you to eat is so low, that many times you are not getting all of the proper nutrients you need throughout your day. Fad diets can also be very difficult to stay consistent with. They are usually so extreme that an individual can only maintain the diet for so long and then the weight that has been lost can be very easy to regain.   
Carol Cottrill
Nutrition & Dietetics

Restrictive dieting always ends in one of two ways

  • Lose the weight and gain it back, plus some
  • Lose the weight and obsess over gaining the pounds back by existing within a lifetime of confinement and disordered eating

Personal weight management is an inside job based on one's needs and preferences and cannot be determined by the external dictates of a fad diet. Dieting actually does more harm than good for this reason.

The next time you're tempted by the instant gratification of the latest miracle diet claims, ask yourself how you define success. If you're content with gaining the weight back plus a few pounds then dieting might be for you. If you don't mind a lifetime of deprivation- go for it!  

The truth is there are no tricks and gimmicks to natural and sustainable weight management. Aim for balance, portion control, real foods and moderation and you'll be well on your way to true success!  



Ruth Frechman
Nutrition & Dietetics

I have never heard of a fad diet offering health benefits. Usually fad diets lack important nutrients, or they are very low in calories. In the long term these types of diets may be harmful for health. However, for some reason fad diets seems to appeal to people. Maybe because they often promise quick weight loss. Just remember...Slow and steady wins the race. Watch your portions sizes. Eat plenty of fruits and veggies. 

While fad diets may help you lose weight in the short term, they won't help you keep the weight off for the long haul. They won't help you improve your health, either. The simple fact is, the key to losing weight for the long term is eating a balanced, healthy diet.
Today's fad diets run the gamut from disappointing to dangerous. The short-term health risks and negative side effects correspond with how extreme the fad diet is. With low-carb diets, for instance, these range from marginal deficiencies of key vitamins and minerals to light-headedness and nausea. Incorporating complex carbohydrates provides many important vitamins and minerals, and when eaten in moderation, is part of a healthy diet.

To reap the many benefits of weight loss -- from improved physical and mental health to having an entire wardrobe in a single size that you're happy with -- you need to take the weight off and keep it off for an extended period. There is not a fad diet available that has shown it can make that happen.

Weight Watchers offers a comprehensive approach to weight loss that can help you reach your goals.
Brian Tanzer
Nutrition & Dietetics

Diets are not the answer to long-term weight management and optimal health. There are thousands of books on dieting and nutrition yet 1 in 3 Americans are currently obese. It is predicted that by the year 2050 1 in 3 people with have Type 2 diabetes. The answer to long-term weight loss is very simple, yet we try to make it complicated; which also make sit lucrative for many people who claim to be nutrition experts.

The answer to long-term weight management is to make small changes in your diet over time incorporating whole natural foods and eliminating refined processed foods. There's no need to eliminate any one particular food group i.e. carbohydrates, but, consume these foods in there whole natural, unrefined state in very small amounts. Combining this with lean protein and healthy fats i.e. fish, chicken, nuts, seeds, olive oil, etc. and before you realize it you have made significant changes in your diet, regardless of how long it may take. Going on and off the latest fad diet is unnecessary and may in fact be detrimental to your overall health. A healthy eating plan combined with regular exercise is the answer to long-term weight management. The problem is, there aren't enough physicians and other healthcare providers educating patients about these issues, so, the patients is left to educate themselves and we have seen the result of this; the rate of obesity in the United States continuing to get increase.

Sarah Worden
Nutrition & Dietetics

Fad diets generally cause a lot of weight loss quickly, usually because calories are very restricted on these diets. A person can stick to a low calorie diet for a short while and see some positive results, but it is difficult (and unhealthy) to stick to a very low calorie diet long-term. Also, these diets often focus on a particular food or food group or avoid a particular food group (think grapefruit diet, low carb diet, the cookie diet) and limit or provide too much of a certain nutrient or nutrients. Fad diets are generally not balanced diets. Our bodies are made to thrive on a balanced diet with food from a variety of food groups. For the best results and the healthiest body, it is best for one to eat a balanced diet and stay away from fads. 

Amy Jamieson-Petonic
Nutrition & Dietetics

Fad diets can be harmful because many eliminate entire food groups, and can lead to nutrient deficiencies. For example, if you eliminate all carbohydrates, such grains, fruit and low fat dairy, as with a high protein diet, you can potentially be eliminating B Vitamins, calcium and other nutrients that are important for normal activities. 


Jessica Crandall
Nutrition & Dietetics

Fad diets often eliminate certain food groups, therefore leading to an unbalanced diet. This can leave you feeling deprived and is often not considered a long term strategy for weight loss and can be bad for your health. You should always contact you doctor and dietitian to discuss dietary changes.

Judy Caplan
Nutrition & Dietetics
Mainly because they are not teaching long term strategies for weight control. Building health is a daily habit, jumping from one fad diet to the next does not mean you are nourishing your body and in fact may mean you are harming it. Long term healthy eating is what builds health, not a week or two on a crazy regime.
If you are trying to lose weight, steer clear of fad diets and complicated weight-loss schemes. According to a 2009 study published in the journal Appetite, many diet plans are so complex that people simply give up. The study reported that participants were more likely to abandon their diets if they could not remember all the rules or keep track of the plan. Look for a program that you can understand and sustain. If you don’t have time to make fresh fruit or vegetable juices every day, a diet that includes them is probably not going to work for you. Also, don’t believe the hype of “instant” weight-loss products. You may see amazing results at first, but be sure to research how well people maintain the loss.
Cindy Guirino
Nutrition & Dietetics
FAD diets should stand for FORGET ANOTHER DIET!  Instead FOCUS on the foods that provide your body with energy and nutrition: nutrient-dense whole foods.  If you fill your plate with what matters instead of some new trend or fad way of eating, you will gain GOOD HEALTH!

Continue Learning about Dieting Risks

3 Reasons to Stop Yo-Yo Dieting
3 Reasons to Stop Yo-Yo Dieting
Year after year, polls put weight loss among the top New Year’s resolutions. It’s a worthwhile goal, but not if you opt for a crash diet—a sudden, dra...
Read More
Is a diet that eliminates carbohydrates healthy?
Honor Society of Nursing (STTI)Honor Society of Nursing (STTI)
Several popular diets emphasize eating low amounts of carbohydrates in order to lose weight. Individ...
More Answers
What are the possible side effects of a slow-carb diet?
Tim FerrissTim Ferriss
If you get headaches or have other symptoms of low blood sugar, 90% of the time it will be because y...
More Answers
Why Are Certain Fad Diets Bad for My Health?
Why Are Certain Fad Diets Bad for My Health?

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.