By Jeannie Versagli, R.D., LDN
Why are Fad Diets Bad?
Fad diets are trendy weight loss programs that promise a quick solution for weight loss. These diets may work initially because they require an overall decrease in caloric intake. However, they are deficient in nutrients because they often omit entire food groups. Dehydration, weakness, fatigue, and headaches accompany these plans. Why? Because they lack the proper fuel for the body to function correctly.
A common thread with these diets is that they offer a temporary solution to a lifelong problem. When people go off these diets, here’s what happens: they gain all their weight back and then some. These diets fail to teach people how to eat healthy and address the necessary behavioral changes that promote weight loss for a lifetime.

Fad Diet Promises That Don’t Hold Up
- Rapid weight loss – Weight that is lost quickly results from muscle and water loss, not fat loss. Weight loss of more than 2 pounds per week is not considered a healthy rate of weight loss.
- Limitations of foods – Many fad diets (for example, the cabbage soup diet or grapefruit diet) limit certain foods and promote unlimited amounts of other foods. These diets are bland, difficult to follow, and lack the nutrients that are important to overall health.
- One size does not fit all – Each person is different and requires an individual approach to weight loss. A good program focuses on the individual’s unique energy needs, macros, behavior modifications, and exercise habits. For example: if you work out frequently, consuming 2,000 or even 2,500 calories in a day may not be enough to fuel your body properly.
- Promise of a quick fix – When it comes to weight loss, there is no quick fix. It takes time and commitment to accomplish a healthy weight loss. The goal should be to lose body fat, not muscle and water weight. The only way to decrease body fat is to commit to following a balanced diet with and exercise program over time.
- Makes claims not backed by science – Any nutrition statements and or claims should be backed up by science. Do your homework on the information that you read. Spend some time and research where the diet’s information is coming from before you start any new and popular diets.
- Rigid menu – These diet plans are difficult to follow and do not teach people how to eat healthy. When considering a diet, always ask the question, “can I eat like this the rest of my life?” If the answer is no, then it is not a successful plan for weight loss.
- No need to exercise – Weight loss without exercise creates an unhealthy outcome. It is recommended to exercise to achieve a healthy weight loss. A combination of diet and exercise allows the body to maintain and or improve muscle mass through strength training, preserve bone density through weight-bearing exercise, improve cardiovascular health via cardio, improve blood sugar levels, and improve lipid levels.
- Special combination diets – There is no scientific evidence that eating combinations of foods together improves or promotes weight loss.

To accomplish a healthy approach to weight loss, focus not on what a fad diet can give you in the short term. Look to lifelong changes to healthy eating that offer variety and flexibility along with an exercise program that enhances your life.
Focus on eating from the Mediterranean, DASH, or Flexitarian diet and include daily exercise to accomplish a lifetime of healthy weight status. Connect with a registered dietitian to help you develop and understand a healthy eating program. Remember that nutrition is your path to wellness.
Adapted from https://www.eatright.org/health/ weight-loss/fad-diets/staying-away-from-fad-diets
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