Hidden Side Effects Of The Most Popular Diets

Before you take a medication, you probably are warned of the side effects. Potential downsides like diarrhea, depression and migraines are listed on the label. But when you turn to a diet to treat some aspect of your health (whether it be your weight, mood or gut health) you aren't always awarded the same courtesy. People often see going on a diet as something common and casual. It's just a diet! What's the big deal? People go on diets all the time. But diets come with their consequences, too. You're just not always warned about them.

You're probably often faced with information about the benefits of various diets. You might have read about the best diets for weight loss or the best foods to eat for your heart. Maybe your coworker told you all about how the newest diet fad cured her acne or helped improve his mood. However, you're much less often faced with information about the drawbacks of following a diet. But that doesn't mean these downsides don't exist.

"Overall, dieting for the sake of weight loss or manipulating your body shape or size is not a harmless pursuit," says Cara Harbstreet, MS RD LD, of Street Smart Nutrition. "Yes, we can agree that there are many methods that can potentially result in short-term weight loss. No one is denying that there is efficacy behind some (not all) of these methods. However, what we need to also question is the long-term efficacy of dieting and the potential side effects."

So just like you would before taking a new medication, it's important you read up on the side effects of the new diet you're considering. Before you decide to try it, you want all the information necessary to make an informed decision. Here are some hidden side effects of a few of the most popular diets — and of all diets in general.

Carbohydrates are the body's preferred source of energy; if you limit them, you may feel the effect. Sugars and starches are utilized in a number of processes in the body. According to Ginger Hultin, spokesperson for the Academy of Nutrition and Dietetics and owner of ChampagneNutrition, lethargy is often a side effect of low-carb dieting.

Every person's carbohydrate needs are different, says registered dietitian Jillian Greaves. Certain low-carb diets may restrict carbs to a level that's too low. "If you're overly restricting carbohydrates, this is a form of stress on the body that can disrupt normal endocrine function," Greaves says. Your endocrine system, responsible for your hormones, is related to many other systems in the body. "This disruption may contribute to cravings, an irregular or stopped menstrual cycle, hypoglycemia, mood swings, anxiety, chronic fatigue, suppressed immune function and thyroid disturbances."

Your body prefers to use carbs for a number of basic brain functions; so eating too few of them can cause your brain to fight back. "Cutting out carbs through any low-carb diet (including paleo and keto) can set a person up for binge eating in part because when we don't eat enough carbohydrates, our body releases a brain chemical called neuropeptide Y," says registered dietitian Julie Dillon. "This chemical's job is to tell our body to eat carbs — and eat them now." When a person's brain is flooded with this chemical, it can result in an animal-like instinct to go crazy on carbs — attack a plate of brownies or eat an entire pizza, for example. "It can feel like every cell in your body is demanding carbs, which can lead you to feel that you lack willpower," Dillon explains. "But it has nothing to do with discipline. Rather, this neurochemical is trying to save your body from experiencing fainting, dizziness or worse!"

Low-fat diets have been popularly recommended for decades. These diets involve limiting foods with both unsaturated and saturated fats. Whether or not these diets are effective or healthy is highly controversial, especially in recent years, as evidence of the health benefits of fats accumulates. However, conclusions have not yet been drawn by the medical community. Regardless of whether or not there are benefits to a low-fat diet, here are some side effects you should know about.

Certain vitamins, including vitamins A, D, E and K, are fat-soluble, meaning that your body needs fats in order to absorb them. If you do not have enough fats in your body, the vitamins you eat may pass through your system unabsorbed. This can result in nutrient deficiencies, which may cause other negative health effects.

High-fat foods such as avocados, nuts and oils are some of the top foods neurologists recommend eating for brain health. Your brain, which is actually made up of 80 percent fat, relies on dietary fats to function. If you don't eat enough of this nutrient, you may miss out on some of the brain-boosting benefits of dietary fats including better memory, lower risk of dementia and Alzheimer's, and better focus and concentration.

"This is far and away the top diet that people cite when they seek my support for disordered eating and healing their relationship with food," says Harbstreet of Street Smart Nutrition. "Often, this comes after multiple rounds of the 30-day program where they initially wanted to eat more healthfully but became increasingly disordered with each successive round. It's harmful because it's promoted as a 'lifestyle' not a diet, yet the food rules are rigid and inflexible and lack evidence to back up the sensational claims." The most common effects Harbstreet sees in patients are orthorexic behaviors — meaning an unhealthy obsession with "healthy" eating. Additionally, those who complete the 30 days of dieting often report feeling large amounts of anxiety once the 30 days are over. Transitioning back into eating normally without fearing certain foods can be extremely stressful for the dieter.

The keto diet is a popular diet trend based on the idea that if you eat a small enough number of carbohydrates, your body will be forced to burn fat for energy in a state called ketosis. On the diet, you can eat large amounts of fatty foods and animal proteins, but can only eat very small amounts of foods that are sources of sugar, such as fruit, grains and vegetables with carbohydrates like sweet potatoes or carrots. Whether or not the keto diet is actually safe, many have turned to the diet (which originated as a last-resort treatment for epilepsy in children) in order to lose weight. However, this diet can cause a number of other reactions in the body. Here are some side effects you should know.

Dietary fiber, which is found in whole grains, fruits and many other carbohydrate-rich foods eschewed by the keto diet, is essential for maintaining proper digestion. Cutting many of these foods from your diet to remain in ketosis may back things up. One study testing the efficacy of the keto diet to manage epilepsy in children showed that a majority of patients on the keto diet complained of constipation.

"The keto diet may be hard on digestion, as many people find a high-fat diet aggravates acid reflux," says Oyston. Eating large amounts of cheese, red meat and these other common heartburn triggers could become really painful.

Many who try the keto diet experience a set of symptoms referred to as the "keto flu." In some studies, the keto flu afflicted over a third of those who attempted the diet. Symptoms vary, but they generally include nausea, vomiting, constipation, diarrhea, headache, irritability, weakness, muscle cramps and soreness, dizziness, poor concentration, stomach pain, difficulty sleeping and sugar cravings. Reportedly, the symptoms subside after a week or two, but some people don't shake them off as quickly.

Many people believe in the philosophy "calories in, calories out," but this theory fails to take metabolism into account. "Calorie restriction triggers our bodies' survival mechanism," explains Alissa Rumsey, MS, RD, nutrition therapist and owner of Alissa Rumsey Nutrition and Wellness . "When you eat too few calories, your body thinks you are starving so it decreases your metabolism and increases fat storage." This habit is one of many that could slow down your metabolism over time.

Low-calorie diets may seem like a benign way to prevent overeating, but research shows that they have their consequences. Some studies show that low-calorie diets result in an increase in the stress hormone cortisol. Cortisol is released in many scenarios wherein your body is under duress — lack of sleep, eating tons of sugar and drinking excessive amounts of alcohol, for example. Too much cortisol in your body can cause some serious negative health effects over time.

Calorie counting is a form of food tracking, and it involves keeping tabs on what you're eating every day, whether in your head, an app or some form of food diary. "This can trigger obsessive behaviors, guilt and anxiety around food," says Rumsey. These behaviors can have detrimental effects on mental health over time or even lead to disordered eating, she explains.

While specific diets have their individual side effects, all diets share a few important side effects. Before you pursue weight loss by limiting your food choices with any diet, here are a few side effects you should be prepared to face.

Weight cycling occurs when a person repeatedly loses and regains weight, which often results in a net weight gain over time. "Long-term diet research (two years or longer) suggest that most people regain all the weight lost during a diet, whether they stick to the diet or not," Dillon says. "In fact, many regain more weight than was lost in the first place." Weight cycling is not only stressful for the dieter; it's also connected to other health complications such as increased insulin, blood sugar, blood pressure and cholesterol. It also is connected to a slower metabolism.

You might think that going on a diet would make you feel better about your body, but research shows quite the opposite. A study of college students showed that for men and women, dieting (even diets described as "normal" in severity) resulted in an increased concern with weight and a lower self-esteem. Another larger study showed that both men and women who reported dieting behaviors were less likely to have a positive body image. Instead of dieting, consider trying one of these simple ways to feel better about your body right now.