Got a Crush on a Crash Diet?

NUTRITION CORNER: Got a crush on a crash diet? Check the research

A new diet seems to hit the headlines every week: the Nordic! HMR! Alkaline! 5:2! The promises can sound great, but be sure to slow down and check with the experts. Your health is on the line! Let’s take a deeper look at what the research says about three diets that are hot today—especially since it’s March, National Nutrition Month.

Intermittent fasting

With intermittent fasting, you follow various patterns of fasting through the day or week. The three main patterns are alternate-day fasting (alternating a day with no food with a day of unrestricted eating), modified fasting (days of partial fasting, meaning 25% fewer calories on those days, and then other days with unrestricted eating) and time-restricted feeding (no eating between certain hours). Other names for this diet trend include the Fast Diet, 5:2 or 8/16 diet.

Research shows some promise, with rat and mice studies demonstrating weight loss while preserving lean muscle. However, more studies are needed in human populations for weight loss, as well as to determine how and if intermittent fasting differs in general from daily caloric restriction.

Should I try it? There are several valid concerns about this diet. For starters intermittent fasting was ranked 33 out of 41 by 2019 US News & World Report for 2019 Best Overall Diet. Second, be wary of long-term bouts of fasting to make sure you are meeting your nutrient requirements. Lastly, fasting is not recommended for those with diabetes or a history of eating disorders, pregnant or breastfeeding women, or if you have a health condition where medications are taken only with food.

Ketogenic diet

The ketogenic or keto (“KEY-toe”) diet is a calorie-restrictive program that mandates a high fat intake and a low carbohydrate intake to put the body in a state of ketosis. Ketosis occurs when your body does not have enough glucose (or sugars) available to fuel the brain and maintain cellular function, and so it starts to break down fatty acids into ketones. Maintaining a state of ketosis requires you to eat no more than 20-50g of carbohydrates per day, depending on your total calorie intake.

Research shows that like most calorie-restrictive diets, this one works temporarily. Studies also found that keto dieters have improved satiety (the sense of fullness) levels because of the high fat recommendations, and because the appetite-stimulating hormone is reduced during ketosis. Another study showed that those on the keto diet improved insulin sensitivity; however, it also noticed that they are more fatigued than their counterparts and that both their cholesterol (both LDL and HDL) and certain inflammatory markers increased. Additionally, there are risks for developing kidney stones, bone fractures and constipation because of micronutrient deficiencies and limited fiber intake. Often, it is recommended to supplement the keto diet with vitamins and minerals to get the proper amounts of nutrients in ketosis.

Should I try it? The keto diet was ranked 38 out of 41 by US News & World Reports, which demonstrates that it isn’t the most favorable eating plan for most. If you do try it, it’s important to work with a physician and dietitian to make sure you are meeting your micronutrient needs or managing any medication interactions. This diet plan can also be socially isolating due to its strict nature, so it is important to be on the watch for mental health effects.

Whole30 diet

The Whole30 diet is a popular eating plan to “reset” digestion and potentially provide some weight loss benefits. For 30 days, dieters follow a plan that promotes fresh foods while eliminating many processed options like salty snacks and desserts. It also eliminates dairy; grains; legumes; alcohol; additives like MSG, carrageenan or sulfites; and peanut butter—all for claims of better digestion, skin health, metabolism and overall sense of well-being. Snacking is frowned upon and exercise is promoted. At day 30, dieters reintroduce all foods slowly to determine how the body responds to each addition.

Should I try it? This diet comes with lots of promises but little research to back it up, so more study is needed. Whole30 is ranked 38 out of 41 in best overall diet, showing again the limited benefits for embarking on this journey. However, this plan does take people back to the kitchen to cook whole foods, which is helpful for consuming the recommended fruits and vegetables. If starting this plan, make sure to have a strong support system, good meal planning skills and the dedication to complete it.

Crash diets vs. healthy lifestyle changes

With any eating plan, it’s important to tell your health care team if you are dieting for longer than a month or two to ensure nutrient deficiencies are minimized and, in extreme cases, lab work is monitored. Diets rarely lead to long-term health or even weight loss, yet they often promote food restriction, are inflexible and almost seem a punishment for one’s weight and body size.

So, what works better? Aim for lifestyle changes that switch your mindset to eating for health not size. This approach includes supporting and acknowledging your relationship with food, being flexible with eating, and accepting and welcoming all foods that support our physical health and emotional health. We can all be healthy in our own way and time, especially with the individualized help of our health care team. Think long term!