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Debunked by a Dietitian: Fad Diets, Part One

The Good and the Bad About Limited Time Detoxes

This is the first in a two-part series on the facts about fad diets, focusing on short-term programs. To learn about ongoing diets like paleo or gluten-free, please read part two.

Interest in eating well is often accompanied by a rise in fad diets. But the science behind each new fad can vary and restrictive diets in particular can present certain obstacles for your health.

Many popular trends, particularly regarding weight loss, involve strict elimination for a limited time period, ranging from a few days to a full month. These types of diets are not intended for more than a brief period of time. While they can offer a jump-start to healthy eating or a hard stop on bad habits, they are not in and of themselves healthy practices and as a result, many benefits – such as weight loss – are only temporary without long-term change.

Here’s what Edye Wagner, MBA, RD, LDN, CDE, a nutrition expert at Northwestern Medicine, had to say about the most common of these trends.

“Keep in mind,” Wagner cautions. “Many of these diets aren't a good long-term solution. For lasting results, your best bet is to eat a healthy diet based on fruits and vegetables, whole grains, and lean sources of protein.”

Cleanses and Juicing

Cleanses, detox diets and juicing are structured around eliminating most food groups for a given period. There is very little research to suggest that these diets remove any toxins from the body and the decision to start a cleanse can involve many factors.

  • The Good: Eliminating processed foods is good for you.
  • The Bad: Eliminating so many food groups also eliminates many essential vitamins and minerals found in other non-processed foods. Colon cleansing can also cause cramping, bloating, nausea and vomiting.
  • The Verdict: “There is no good evidence to support these diets,” says Wagner.

Sugar Cleanse

As the name suggests, the sugar cleanse eliminates all forms of sugar for at least 21 days. Sugar, however, comes in many forms, with many names, and is in fact found in most food – making the strategy sound deceptively simple. Not only are you eliminating sodas, desserts and candy, you’re also abstaining from processed foods, fruit drinks and condiments, as well as anything with white, brown or raw sugar, fructose, maltose, sorbitol, evaporated cane juice, xylitol and barley malt on the nutrition label.

  • The Good: Eliminating sugar eliminates the potential bad effects of sugar: an inefficient metabolism, inflammation, and elevated risk for bad cholesterol, high blood pressure and diabetes. The sugar cleanse can also help you lose weight, give you more energy, help you sleep better and feel less moody, achy and spaced out.
  • The Bad: A sugar cleanse leaves you with very few food choices. Moreover, many of the benefits like weight loss are only temporary unless you adopt long-term sugar reduction.
  • The Verdict: “The sugar cleanse diet can be complete in nutrients,” says Wagner. “But following it takes a great deal of work.”

The Whole 30

The latest trend, the Whole 30 is a highly restrictive diet that’s intended to help redefine your relationship with food. It eliminates whole food groups (grains, dairy, legumes and all sugar) for 30 days, at which point foods are gradually reintroduced allowing you to identify how certain foods affect your body and health.

  • The Good: The Whole 30 can promote healthy nutritional choices and four weeks is a good start for forming habits. It’s also been said to improve energy, sleep, digestive issues and weight loss.
  • The Bad: Many of the food groups eliminated actually promote health. Calcium, vitamin D, fiber and protein levels can all suffer as a result of the restrictions.
  • The Verdict: “The Whole 30 is an elimination type diet that is best done with a registered dietitian and the advice of a physician,” says Wagner.

Intermittent Fasting

Religious reasons notwithstanding, intermittent fasting is also a weight loss or clean eating trend. People may choose to ‘go food-free’ for 24 hours once or twice a week or ‘eat like a warrior,’ meaning they fast and then eat one large meal. Similarly, some people will follow an ‘every other day’ diet, alternating fasting and feasting days, where they will eat very little one day and eat without restraint the following.

  • The Good: Some reports tie intermittent fasting to reduced blood pressure and inflammation as well as increased fat loss.
  • The Bad: Fasting is often accompanied by rebound eating, which is when people eat much larger portions than they normally would as a result of going without food. Fasting is also associated with poorer sleep, muscle loss and nutritional deficiency.
  • The Verdict: Says Wagner, “The jury is still out to whether intermittent fasting has any health benefits.”