How Crash Diets Can Trigger Heart Palpitations

With the obesity epidemic showing no signs of abating, it seems that everyone's on the lookout for a magic-bullet diet to shed pounds quickly and effortlessly. But crash diets rarely deliver, and they may even lead to health complications. Exhibit A: heart palpitations.

"Heart palpitations are the sensation of an abnormal heartbeat, an extra heartbeat, a fast heartbeat or slow heart beating," explains Kenneth A. Ellenbogen, MD, a professor and chair of the cardiology division at the Virginia Commonwealth University School of Medicine in Richmond.

Heart palpitations can take many forms. According to Harvard Health, you might feel fluttering, throbbing, murmuring, pounding or a heart-skipping sensation in the neck as well as the chest.

To be sure, according to the National Heart, Lung, and Blood Institute (NHLBI), heart palpitations are not uncommon and, in most cases, harmless. More often than not, they go away on their own, with no medical intervention required.

But there is some uncertainty. "Heart palpitations may be benign, or they may represent serious heart rhythm properties," warns Dr. Ellenbogen. "In some instances, heart palpitations are a sign of significant heart trouble."

And for those who've embarked on a crash diet in an attempt to lose weight fast, heart palpitations may be an unwanted side effect, says Penn Medicine.

Read more: How to Safely Lose 5 Pounds in One Week

The use of so-called diet pills is one reason you might experience heart palpitations, explains Lona Sandon, PhD, RDN, LD, a registered dietitian and associate professor of nutrition at the University of Texas Southwestern Medical Center in Dallas.

"Rapid heart rate is a side effect of some U.S. Food and Drug Administration-approved weight loss medications and several over-the-counter diet aids or supplements that people may use to attempt to lose weight," she notes.

Why? Some of those pills contain very high amounts of caffeine, a known trigger for heart palpitations, according to Harvard Health. Not every dieter will experience palpitations as a result, says Sandon, but "caffeine is a stimulant and can increase heart rate, and some people are more sensitive to caffeine's effects than others."

Dehydration is another palpitation trigger, according to Harvard Health. And crash diets are often implicated in the onset of serious dehydration, says Sandon. "Electrolyte imbalances can occur with highly restrictive diets below 800 calories or with highly restrictive detox type regimens that may lead to electrolyte loses due to diuretic effects or, sometimes, diarrhea," she notes.

A contributing factor is low blood sugar (hypoglycemia). "Limiting food intake can lead to blood glucose levels on the low end of normal," Sandon warns. "People may feel some symptoms of hypoglycemia, such as dizziness, headache or difficulty concentrating."

Dips in blood sugar levels can, in turn, set off heart palpitations, according to Harvard Health. The risk for this is typically higher among dieters with a history of heart disease, anemia or hyperthyroidism (an overactive thyroid gland). Sandon adds that people with diabetes are more prone to hypoglycemia and, therefore, palpitations when following a highly restrictive weight-loss program.

Read more: What Really Happens to Your Body When You Have Caffeine

What's the best way to lose weight without prompting palpitations? "First, drop the diet mentality," advises Sandon. Forget fads. "If they worked, you wouldn't have to be trying the latest fad once again to lose weight," she says. "If you can't do it as a long-term lifestyle, don't do it."

Her secrets for success are to fill your plate with mostly fruits and vegetables and a moderate amount of protein. Choose whole grains in place of refined and cut back on the amount and how often you eat foods with added sugars and unhealthy fats.

Add exercise, too. "Being physically active every day is the best way to keep from gaining weight and maintaining any weight loss," says Sandon. "This is just as important, if not more important, than what you eat."