The Skinny on Fad Diets

MUSC Health Metabolic & Bariatric Surgery Program
August 28, 2020

Whether you’re scrolling through social media, talking to friends, or flipping through a magazine, it’s likely that you have seen or heard a promotion for a diet that boasts of amazing and fast results: Eat this and lose 20 pounds in 2 weeks! Drink this and watch the pounds melt away! Cut out this food and drop 4 dress sizes! These claims seem too good to be true (and maybe that’s because they are). During the August MUSC Metabolic & Bariatric Surgery Program support group meeting, we discussed nutrition hot topics and one of the most talked about nutrition topics is fad diets.

What are Fad Diets?

A fad diet is any diet that is only popular for a short period of time and is not backed by any professional nutrition recommendations. These diets may make some of the outrageous claims listed above or may have a more subtle marketing standpoint. The fad diets we discussed in the August meeting are the keto diet, intermittent fasting and skinny teas.

Keto Diet

The keto diet promotes a diet of minimal carbohydrates, some protein, and a high fat intake. This diet originated in the 1920’s as a treatment for patients with epilepsy or frequent seizures. To understand why keto can help those with seizures, you have to look at what this diet does to your body.

Carbohydrates become a quick energy source by breaking down into glucose, which the body can use to fuel your activities. Your brain needs glucose to function and actually prefers it to other energy sources. When on a low-carbohydrate diet like keto, there isn’t enough glucose to fuel your body. After a few weeks your body will switch to producing ketones as an energy source, hence the name the keto diet. Ketones are produced when your body begins to break down fatty acids through a process called ketosis. The brain functions differently when using ketones and this is what benefits those with frequent seizures. However, the keto diet is not for everyone.

In recent years, the keto diet has become more associated with rapid weight loss than helping those with seizures. One aspect of this diet is the weight loss and loss of hunger that results from the low-carbohydrate and high fat diet.

While these claims sound promising, be sure to look at some of the not so promising effects of keto. As we discussed above, the brain loves glucose! While the brain can function on ketones, glucose is still its most compatible form of energy. Additionally, switching from glucose to ketones causes a shift in how the body is run and can cause extreme fatigue known as the keto flu. Rapid weight loss sounds great, but the results are often not sustainable. Cutting out a whole food group is not sustainable long term without being medically monitored and can lead to vitamin and mineral deficiencies from leaving certain whole grains, fruits, and veggies out of your meals. A more dangerous aspect of the keto diet is the risk of ketoacidosis. Diabetic ketoacidosis results from high ketone levels in the blood. High levels of ketones can cause blood to become more acidic and can act like a poison in your circulatory system. Keto is also not recommended for those who have undergone bariatric surgery due to the high fat content. Bariatric surgeries reroute the passage of food and a high fat diet is not well absorbed. For these reasons, it is important to not start this diet unless it has been recommended by your healthcare provider. If it has been recommended, it is important to see a dietitian who can help you make a safe meal plan.

Intermittent Fasting

A popular diet among the fitness and weight loss community is intermittent fasting. There are two main types, 5:2 intermittent fasting and time restricted intermittent fasting. 5:2 intermittent fasting consists of eating “normally” 5 days a week with normal defined as your regular calorie intake. The remaining 2 days of the week are considered the fasting days. On fasting days, you consume around 25% of your normal calorie intake. The other form, time-restricted intermittent fasting, is the most common type. This consists of defining the hours in which you can eat. The most common time frame is 1 or 2 pm to 7pm.

Eating minimal calories 2 days a week or limiting the hours that you can eat make some people feel more in control of their calorie intake without actually counting calories. Not being reliant on calorie counting is a popular aspect of this diet as well as potential weight loss, claims of better digestion, and the aspect that some people prefer to work out in a fasted state. 

It is also important to consider why this diet may not be beneficial. First, it is not sustainable. Putting your body on a schedule as intense as intermittent fasting can interfere with sensing your body's natural hunger and fullness cues. Undereating during certain periods of time can lead to overeating during the times that you are allowing yourself to eat. Not eating for long periods of time can also lead to fatigue which can affect your workouts and your body.

Overall, intermittent fasting works for some but it is not recommended for most people because of the inability to sustain a diet with restrictions like these. This diet can be especially dangerous for those with diabetes and those who have undergone bariatric surgery. The long periods of fasting can cause dangerous drops in blood sugar. In contrast, the hours of eating following the drop in blood sugar can cause the blood sugar to jump, which can be dangerous for those that suffer from diabetes. Bariatric patients are instructed to eat frequent, small, and protein packed meals. Intermittent fasting consists of larger meals on certain days or during certain hours of the day and is therefore not recommended. If you have any concerns about your diet or have questions about intermittent fasting, contact your dietitian!

Skinny Teas

Skinny teas and detox teas have risen in popularity due to celebrity endorsements and social media advertisements. These teas claim anything from being able to cleanse your body to promoting weight loss without changing your diet or activity level. However, just looking at the ingredient label for these teas can give you all of the information that you need to know.

The one benefit of these teas is that they may help you lose weight. However, just drinking tea and not making sustainable changes in your diet will most likely not have an effect. Detox teas claim to cleanse your body, however, most people don’t have a need for this. Our kidneys and liver work to cleanse our bodies without the help of outside teas or supplements. The ingredients in these teas that are responsible for the weight loss and detox effects are diuretics or laxatives. These may appear on the label by name or most likely they will be in the form of a natural laxative such as dandelion leaf or senna leaf. This can be dangerous, especially for those who have had bariatric surgery, because the laxative can lead to nutrient malabsorption and dehydration.

In Conclusion

Fad diets can be easy to spot if you look at what the diet promises. If the claims look too good to be true, they probably are. Trying a fad diet is not failing by any means. Most people on these diets are just trying to lead healthier lives. When choosing what to eat next, listen to your body's hunger and fullness cues. Eat food that you enjoy and remember that everything is good in moderation. Be kind to yourself and do what is best to nourish your body! 

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About the Author

MUSC Health Metabolic & Bariatric Surgery Program
With 20+ years of experience combined, Registered Dieticians Amanda, Haley and Cher facilitate behavior change through nutrition counseling for weight loss and maintenance with children through adults.