Food for thought

5 popular fad diets and how to advise your patients on them

The countless diets, dietary supplements and unfiltered information disseminated on the internet often confuse and overly complicate the fundamental pillars of a healthy diet and can leave people wondering how to truly eat healthfully.


Starting on the path to a healthier lifestyle can be challenging. The countless diets, dietary supplements and unfiltered information disseminated on the internet often confuse and overly complicate the fundamental pillars of a healthy diet and can leave people wondering how to truly eat healthfully.

Since reaching out to a doctor is the best way to go about making the best diet decision, doctors need to be prepared to advise patients on which route to take. As a registered dietitian, I am happy to share my insights on nutrition and health with the osteopathic medical community. Below are five popular and well-known fad diets and the effects they might have on your patients should they decide to partake in one.

The Academy of Nutrition and Dietetics is a great source for evidence-based information related to food and nutrition. Their website includes patient education, healthy recipes and a search for registered dietitians by location.

Whole 30

This diet emphasizes eliminating all grains, legumes, soy, dairy, sugar, artificial and natural sugars, alcohol, carrageenan, MSG (monosodium glutamate) and sulfites. Participants are advised to abstain from these foods for a total of 30 days. While the name includes the word “whole,” many healthy and nutrient-dense foods like whole grains are excluded from the list.

The restrictive properties of this diet raise concerns regarding nutrient deficiency risks and they may also make long-term adherence challenging.

Apple cider vinegar

This one encourages a diet balanced in fruits, vegetables, whole grains, low-fat dairy and lean proteins with supplemental doses of apple cider vinegar. Participants usually add small amounts of apple cider vinegar to their meals and beverages. The diet claims to promote weight loss, suppress appetite, improve gastrointestinal distress and help manage blood sugars, among other benefits.

Apple cider vinegar can be a component of a healthy diet. However, consuming large amounts of apple cider vinegar may irritate tooth enamel and the gastrointestinal tract. There is also inadequate evidence to support the weight-loss claims, and apple cider vinegar should not replace a healthy, balanced diet and regular exercise.

Intermittent fasting

Variations of this diet include alternate day fasting, modified fasting and time-restricted fasting. The original concept usually recommends a “normal” diet for about five days, followed by fasting for two days in a seven-day week.

People typically consume around 500-600 calories on fasting days, via two small meals and a few snacks. Suggestions for light snacks include lean proteins, vegetables, fruit, water and calorie-free drinks.

Participants are encouraged to partake in vigorous exercise on nonfasting days and light exercise on fasting days.

Many of the studies about intermittent fasting have involved animal subjects with some evidence of improved cognition and longevity. There are a few human studies showing positive associations related to weight loss and risk reduction of chronic diseases like diabetes. The studies with human subjects have frequently had small sample sizes.

Intermittent fasting shifts our body’s fuel sources from primarily carbohydrates and accesses other reservoirs, such as fat, for energy, which may contribute to weight loss.

Presently, intermittent fasting is not a recommended treatment for weight loss or other health conditions. This diet may increase the risk of nutrient deficiencies and health issues for individuals with certain medical conditions like diabetes, pregnant and breastfeeding individuals and those with a history of disordered eating. In addition, this diet may be challenging to follow long term.


This diet is deficient in carbohydrates with high amounts of dietary fat and low to moderate amounts of protein. This ratio of macronutrient distribution shifts the body’s metabolism to favor the use of fats over carbohydrates for energy. While the ketogenic diet can produce fast weight-loss results, the initial weight is mostly water.

The ketogenic diet has been utilized to manage and treat epilepsy, but a physician and dietitian will carefully monitor it in this setting. Ketogenic diets can be unsafe and unsustainable long-term for the general population. There is also a concern for increased risk of heart disease due to high dietary fat and cholesterol intake. To limit carbohydrate intake, many nutrient-rich vegetables and fruits may be excluded, increasing the risk of deficiency of essential vitamins, minerals and fiber.


Many detoxification diet programs recommend eliminating processed foods and foods often associated with sensitivities like dairy, gluten, eggs and nuts. Other programs may recommend eating organic produce, gluten-free whole grains, nuts, seeds and lean protein; however, detox diets are not rooted in science, and our body can naturally “detox” itself through our physiologic metabolic pathways.

There can be significant variability between detoxification programs. In some cases, they can pose risks for some people with complex medical conditions, such as pregnant and breastfeeding populations, diabetics, people on extensive prescription medications and those with a history of eating disorders. Also, like some of the other diets on this list, the restrictive nature of detox diets makes them difficult to adhere to long term.

Eating for optimum health

Overall, trying out fad diets is typically not the suggested route to go. It is best to lose weight slowly and steadily to improve the chances of keeping the weight off and maintaining eating patterns that include the essential macro and micronutrients necessary to optimize our bodily functions. In addition, individuals should stay hydrated with calorie-free beverages, especially water, and eat various fresh fruits, vegetables and lean protein daily to stay healthy.

In general, I advise people to start their day with a healthy breakfast, no matter how small, to provide an initial energy boost and help with satiety throughout the day. I often tell my patients to eat a colorful variety of fruits and vegetables for added vitamins and minerals. Nutritional literacy is essential. It is important to read and understand food labels to combat consumption of excess calories. Physical activity and water intake are also topics that I routinely underscore with people. Both are essential for weight management and overall health.

When providing nutritional counseling to patient’s, I often reference visual aids like MyPlate or Harvard’s Healthy Eating Plate. I will print a copy of these images for my patients to post on their refrigerator or any other location for reference when preparing their daily meals. These education tools do a great job of emphasizing nutrient balance and portion control to combat overeating, nutrient deficiency and macronutrient imbalance.

Editor’s note: The views expressed in this article are the author’s own and do not necessarily represent the views of The DO or the AOA.


  1. Jenna Dionisio, DO

    Great review! Especially helpful as my mother recently started an apple cider vinegar “diet,” and you brought to my attention the adverse effects on tooth enamel and the GI tract. Thank you!

  2. Randall DeArment

    I recommend to my patients
    Facts backed up with research
    No sponsor or sales. Dr is also a great resource

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