Search here...
Nutrition Weight Loss

Why So Many Dietitians Are Against Actual Diets

dietitians against diets

There are plenty of trendy diets out there that people swear by: intermittent fasting, paleo, keto, vegan, whole 30, juicing, and so on.

But why do the experts on the subject, the ones that even have the word “diet” in their title, often advise against ever going on an actual diet?

Here is what they know:

  1. Healthy Eating Is Not Restrictive
  2. People Who Lose Weight Quick Often Gain the Weight Back
  3. The Best Approach to Eating for Weight Loss is Not a Fad-Diet

Note: Dietitians regularly use therapeutic diets to treat specific medical conditions. The following discusses diets for the general healthy population and those attempting to lose weight.

1. Healthy Eating is Not Restrictive

Most fad-diets cut out entire food groups, or restrict certain nutrients such as carbohydrate. This is not the best way to eat for many reasons. One being that you put yourself at risk for missing out on nutrients your body needs.

dietitians against diets

You Can Miss Out On Important Nutrients

All foods have different amounts of carbohydrates, protein, fat, vitamins, minerals, and phytochemicals.

Fiber (a carbohydrate), vitamins, minerals, and phytochemicals are especially important because they help prevent diseases such as cancer and heart disease.

Foods that are grouped together like fruits, meat, or grains, all have similar nutrient profiles that make them unique from other groups. If you cut out a group from your diet, you can become deficient in the unique nutrients that group has to offer.

Let’s say someone wants to become a vegetarian, and cuts out meat entirely. They will have to make sure to find other foods that provide what meat provides (protein, iron, B-vitamins, vitamin E, zinc, and magnesium).

Most people can do this without much of a problem, making a vegetarian diet a healthy choice when done correctly.

But now let’s say someone is trying a new fad-diet that also cuts out certain foods, but this person doesn’t know they need to replace the nutrients lost. For example, the paleo diet cuts out the food group of grains, and the keto diet cuts out both grains and fruit.

dietitians against diets

Grains contain carbohydrate including the highly beneficial fiber, as well as iron, B-vitamins, polyphenols, and phytic acid.

Restricting these nutrients in your body can have detrimental effects, and dieters should be wary. The keto diet, for example, is proven to cause bone mineral loss. (1)

One dietitian who actually recommends the keto diet for weight loss, still acknowledges that the diet is deficient in certain nutrients. Because of this, she also recommends taking a multivitamin and supplements with electrolytes and B-vitamins when on the diet. (2)

Unfortunately, supplements do not have the same benefits of real food, and they are expensive.

It’s also a Pain in the Neck…

Another reason restricting certain foods is not the best way to eat, is simply because it’s a pain! It is straight up confusing and hard work to plan meals around restrictions.

If you have to research for hours what foods you can eat, what foods you can’t eat, and find recipes that don’t have certain ingredients…I’ll let you in on something…it’s a bad diet!

…And It Can Lead to Disordered Eating

A restrictive diet can also lead to disordered eating. You can slowly find yourself becoming stricter and stricter, and feel extremely guilty if you eat something you’re not allowed.

Many people who have developed eating disorders say it started out with harmless dieting and exercise, and then snowballed into extreme restrictions.

Restricting yourself can lead to binge eating. The foods that you label “bad,” “off-limits,” or “cheats” become tantalizing and tempting, which makes you want them even more than before.

When you finally give into the temptation, you over-indulge. You feel guilty and eat way more than you should because the diet is “ruined” anyways.

A healthy relationship with food is not restrictive or stressful. It is intuitive and enjoyable. Intuitive means that you listen to what your mind and body tells you it wants to eat.

It means naturally finding foods that will benefit your body, because you understand what foods are healthy and what foods are not healthy. Then, you decide what to eat based on what you know and how you feel.

2. People Who Lose Weight Quick Often Gain the Weight Back

Fad-diets become popular because a lot of them actually do work in the short-term. People will generally lose weight on any diet that causes them to cut out food groups or reduce the amount they are eating, because it causes a reduction in calories.

The problem is, there is much more to lasting weight loss than what fad-diets provide, and people tend to gain the weight back over time. This is especially true if the weight is lost quickly, which is usually the promise of a fad-diet.

A study published in the American Psychologist, looked to see if calorie-reducing diets were an effective treatment of obesity that should be funded by Medicare.

It found that diets do cause short-term weight loss, but the weight is re-gained after ending the diet. In fact, the longer the time passed after ending the diet, the more weight was gained back. (3)

Here are three reasons why people often gain back weight they quickly lost on a diet:

  1. By following set rules or meal plans, you do not learn how to make healthy choices on your own.
  2. Restrictive diets are not a realistic way of eating for the rest of your life, eventually you go off of the diet.
  3. It is scientifically proven that your body fights to stop losing weight and gain it back when you lose weight too quickly.

Let’s talk about the third reason and the science of weight loss. The recommended rate of weight loss is 1 to 2 pounds per week. That means at most losing 4 to 8 pounds per month. Anything more than this is too quick and unsafe.

When most people set out to lose weight, they have in mind losing weight a lot quicker than this, and some are successful.

But the people who are slow and steady, losing only the 1 to 2 pounds per week, are much more successful in keeping the weight off long-term. (4)

dietitians against diets

An extreme example of why quick weight loss doesn’t work long-term, is what happened to contestants of NBC’s reality show “The Biggest Loser”. It was an extreme weight loss show, where contestants competed to lose the most weight by the end of the season.

The average contestant lost almost 10 pounds per week. Some even lost up to 20 to 30+ pounds in a week.

Most of the contestants have regained the weight they lost, and some are even heavier now than when they started the show. A study on the contestants found out why this was happening.

The study found that after the show, the contestants had a slowed metabolism and lowered leptin levels.

A slowed metabolism makes you put on pounds faster than other people. Not having enough leptin makes you feel hungry non-stop. It’s like their bodies were fighting to gain the weight back that they lost too quickly. (5)

This bodily reaction of a slowed metabolism is found in anyone who loses weight. (5) But the reaction is less extreme when you lose weight at a slow and steady pace.

3. The Best Approach to Eating for Weight Loss is Not a Fad-Diet

According to the USDA, a healthy diet is balanced and has foods from all five food groups throughout the day. (6) This makes sure your body is getting all the nutrients it needs to function well.

Weight loss comes from reducing calories, and you can reduce calories simply by making healthy choices in each food group. These choices include vegetables, fruits, whole grains, lean protein, and low-fat diary.

Remember to Eat Mindfully

Making healthy food choices can be paired with a newer, non-diet approach to weight loss called mindful eating (you may also hear of intuitive eating, a very similar concept). Mindful eating emphasizes being in-tune with your thoughts, feelings, hunger cues and fullness cues.

When you become mindful of what you eat and why, you gain better control of what you are eating. This is important, because it is something people who are overweight often struggle with.

Emerging science is showing mindful eating without worrying about calories can be just as effective for weight loss.

A study published in the Journal of the Academy of Nutrition and Dietetics, found that obese females who followed an intuitive eating approach called “health at every size” had more weight loss, more physical activity, and better eating behaviors than those who followed a structured diet. (7)

Similarly, participants of an eight-week program teaching mindful eating and portion control also had successful weight loss. (8)

Want to learn more about mindful eating? Try the 5-day mindful eating challenge!

The Best Approach

As a dietitian, I believe the key to successful weight loss is a combination of mindful eating and reducing calories.

Mindful eating is the foundation for a healthy relationship with food. Once it is mastered, a person will have all the tools to choose the foods that are most beneficial to their body.

These foods are naturally low in calories and are balanced: vegetables, fruits, whole grains, lean protein, and low-fat dairy. This is the process that will produce healthy, long-term weight loss.

If this post helped you, share it with your friends on social media.


  1. Bergqvist AG et al. Progressive bone mineral content loss in children with intractable epilepsy treated with the ketogenic diet. American Journal of Clinical Nutrition. 2008;88(6):1678-1684.
  2. Amidor, T. Ask the expert: ketosis for weight loss. Today’s Dietitian. 2017;9:12. Link
  3. Mann T et al. Medicare’s search for effective obesity treatments: Diets are not the answer. American Psychologist. 2007;62:220- 233.
  4. Losing Weight: What is healthy weight loss? Centers for Disease Control and Prevention. Feb 13, 2018. Link
  5. Kolata G. After ‘The Biggest Loser,’ their bodies fought to regain weight. The New York Times. May 2, 2016. Link
  6. Choose MyPlate Website. United States Department of Agriculture. Link
  7. Bacon L et al. Size acceptance and intuitive eating improve health for obese, female chronic dieters. Journal of the American Dietetic Assoc 2005;105:929-936.
  8. Rott C et al. An eight-week mindful eating education program increases self efficacy and weight loss. Journal of the American Dietetic Assoc 2008;108(9):A37

Samantha Shuflin, MS, RDN, LDN is a Chicago-based registered dietitian nutritionist (RDN) with a master’s degree in nutrition. She helps busy professionals thrive through nutrition & wellness.



Leave a Comment

Your email address will not be published. Required fields are marked *

error: Content is protected !!