Fad Diets: A Solution or Challenge to Reaching your Weight Loss Goals?
By Kaci Oliver, MS, RD, LDN
The diet and weight loss industry is a $71 billion industry and yet 95% of “diets” fail. Fad diets such as the popular Keto diet and intermittent fasting diet gain millions of followers each year but are they a reasonable solution to long-term weight loss goals? Let’s dive a little deeper into each to determine if they are an appropriate weight loss strategy for you.
Ketogenic “Keto” Diet:
What is it? The Keto diet is a high fat, moderate protein, and low carbohydrate eating plan. A true ketogenic diet is comprised of 75-90% fat, 10% protein (low protein due to the fact that protein can still be converted to glucose), and 5% carbohydrates. It puts participants into a ketogenic state where the body is burning fat instead of glucose for energy. It was originally created to reduce the number of seizures in patients with epilepsy.
Are there benefits; What does the research say? According to research, modest weight loss along with improvements in blood pressure, triglycerides, and HDL cholesterol can be seen within the first 6-12 months of initiating a keto diet. However, the same benefits were not seen after 12 months.
A small study of 39 obese adults placed on a ketogenic diet for 8 weeks found a mean loss of 13% of their starting weight as well as reductions in their insulin levels, blood pressure, and waist and hip circumferences. While on the keto diet, participants experienced lower hunger hormones, which resulted in a decrease in appetite. However, during the 2-week period when they came off the diet, hunger hormones and appetite significantly increased resulting in weight regain.
A meta-analysis of 13 randomized controlled trials following overweight and obese participants for 1-2 years on either low-fat diets or ketogenic diets found that the ketogenic diet produced a small (2 pound) but significantly greater reduction in weight, triglycerides, and blood pressure, and a greater increase in HDL and LDL cholesterol compared with the low-fat diet at one year. However, the compliance to the ketogenic diet declined over time, which may have explained why the weight loss difference declined at 2 years.
What are the risks? Two main problems arise from the keto diet. One being that a diet high in fat, specifically saturated fat, can potentially cause an increase in cholesterol and risk of heart disease. The second problem being that a diet so low in carbohydrates causes people to restrict grains, bread, and even fruits and vegetables, which creates a deficit in many vitamins and minerals. Furthermore, this lifestyle is hard to maintain long term due to the severe restriction it creates.
Along with these long-term risks, short term consequences include flu-like symptoms (often called the “keto flu”) such as: upset stomach, headache, fatigue and dizzy spells.
Patients with liver conditions, thyroid conditions, pancreatic disease, and gallbladder disease or those who have had their gallbladders removed should not follow this form of diet.
Intermittent Fasting:
What is it? Intermittent fasting (IF) involves restricting food (calorie) intake over different periods of time to assist with weight and chronic disease management. There are multiple forms of IF for weight and chronic disease management including, alternate-day fasting, modified IF, and time-restricted feeding.
Alternate-day fasting includes alternating days of restricting calories from 0 to 25% of normal calorie intake on fasting days with eating freely on non-fasting days. Modified IF such as the 5:2 approach follows a calorie restricted diet (~500 calories) on two nonconsecutive days of the week while following a normal calorie intake the remaining 5 days of the week. Time-restricted feeding allows for daily normal calorie intake for a certain time frame while restricting calories throughout the rest of the day. For example, the 16-hour fasting period would allow for an individual to consume calories as normal for 8 hours a day while fasting for the remaining 16 hours.
Are there benefits; What does the research say? Over the last 10 years, studies have found moderate associations between IF and weight loss as well as improved cognitive function, increased longevity and reduced risk of diabetes and certain forms of cancers. A review completed in 2014, revealed that a 12hr time-restricted feeding can lead to lower cholesterol and blood glucose levels as well as a reduction in weight. Furthermore, studies have found that an earlier eating window (i.e., between 8am and 2pm), followed by an 18-hour fasting period could limit hunger and increase amount of fat burned at night.
Whether or not IF is superior to traditional dieting of daily calorie restriction is still in question. IF may yield better compliance than traditional dieting due to the ability to eat freely for some periods of time. However, a recent study showed that both forms of calorie restriction produce the same weight loss results at 6 and 12 months.
Individuals who may tolerate IF style dieting include those who can tolerate longer periods of time without food intake, and those who have trouble with calorie counting or tracking intake.
What are the risks? Risks of extreme calorie restriction on fasting days include hunger, temperature changes, fatigue, headaches, low energy, and irritability. Furthermore, alternating between fasting and non-fasting days can result in gastrointestinal issues such as gas, bloating, and constipation. Several days of fasting and calorie restriction can lead to nutrient deficiencies.
People with type 1 diabetes or those with type 2 diabetes requiring insulin, those who have hypoglycemia, taking medications that require consumption with food, pregnant or breastfeeding, or have a history of an eating disorder should not follow IF dietary pattern.
Bottom Line:
While fad diets such as the keto and intermittent fasting diets have shown short-term benefits in research, their long-term benefits are unknown. Furthermore, severe restrictive fad diets come with risks and are difficult to maintain long-term, which is why 95% of diets fail.
Individualized healthy lifestyle plans developed by professional dietitians and physicians are known to yield better long-term results and are easier to maintain. Our healthcare providers can meet with you to assess your current lifestyle habits and goals in order to develop a plan that is right for you.
However, if you are still eager to try a fad diet, our dietitian and providers can assess whether it is safe for you and ensure you complete the diet successfully.
References:
- Dennett, Carrie (2019 January). The Ketogenic Diet for Weight Loss. Dietitian Today. https://www.todaysdietitian.com/newarchives/0119p26.shtml.
2. White, Dana (2021 June). Intermittent Fasting-An evidenced-based assessment. Dietitian Today. Https://www.todaysdietitian.com/newarchives/JJ21p46.shtml.
