People often turn to low-carb diets for quick weight loss. The high-fat ketogenic diet is especially popular among dieters who favor fast results in lieu of fruit, bread, or chips. But keto isn’t the only way to go low-carb. The diet’s main premise is to force your body into fat burning mode, or ketosis, by eating very few carbs. Dietitians recommend eating no more than 20 to 30 grams of carbs per day to achieve this metabolic state.
Other low-carb diets aren’t nearly so drastic. So what does “low carb” mean, and why does it help with weight loss? We answer your most pressing questions.
What is a carbohydrate?
Every bite of food contains one of three macronutrients: protein, carbohydrates, and fat. Although many foods contain all of these macronutrients, most skew heavily towards one or two. For instance, meat is loaded with protein, bread is mainly carbohydrates, and olive oil is predominantly fat. Your body needs all three to function.
What is a low carb diet?
The phrase “low carb” is commonly used, but it’s not easy to define. That’s because many types of diets can be considered low carb, including Mediterranean, Atkins, or Paleo, according to Kacie Vavrek, registered dietician at The Ohio State University Wexner Medical Center.
“It can be a lot of different things. For some people it’s just reducing the amount of carbs you’re eating in a day. People define it differently,” she tells Men’s Health.
Each diet may have various carb restrictions, but you’re essentially just eating fewer carbohydrates than typical, she says.
“That’s going to mean different things for different people.”
Why do low carb diets cause weight loss?
The pounds seem to fly off once you omit foods like oatmeal, starchy vegetables, fruit, and bread. But all of these are considered nutritious, so what’s the deal?
Carbs are stored in your body as glycogen, which your body uses for energy. Each gram of glycogen contains about three grams of water, says Nick Clayton, C.S.C.S., personal training program manager for the National Strength and Conditioning Association (NSCA). Your body stores that water whenever you eat carbs. In fact, roughly 70 percent of initial weight loss is water, according to Clayton.
Still, low-carb diets can be beneficial, Vavrek explains.
“I actually recommend low carb diets for weight loss for my patients,” she says.
Reducing the amount of carbohydrates in your day may help you reduce overall calories. Plus, you’ll likely eat more nutrient-dense foods and cut out snacks like Doritos.
“The reason I like carb controlled diets is because when we cut carbs we tend to do more protein and healthy fat that help us feel full longer,” Vavrek explains.
What can you eat on a low-carb diet?
No food is off-limits, unless you’re trying the ultra-restrictive keto diet. Low-carb can be adopted under the Mediterranean, DASH, or almost any preferred dietary preference. Although keto is currently trendy, you don’t have to eat lots of fat and omit food groups to be considered low-carb.
Although some people like to count the grams of carbs in food, Vavrek says you don’t need to be so precise. The easiest way is to treat high-carb foods, like bread and rice, as a side dish. Vegetables should make up the majority of your plate, and every meal should include a protein source.
“That’s going to cut a lot of calories,” says Vavrek.
If you’re a numbers person, aim to make 40-45 percent of your daily calories come from carbs, advises Vavrek.
Are low-carb diets healthy?
The effectiveness and benefits of diets depend on execution. A low-carb diet filled with plenty of fruits, vegetables, protein, and healthy fats is ideal. Meals that rely on supplements and omit food groups are less nutritious.
In fact, low-carb diets helped Type 1 diabetes patients control their blood sugar, according to a study published last year in the journal Pediatrics.
And eating higher quality foods–like salmon, leafy greens, and nuts–all of which are low in carbs, was one of five habits that may add 12 years to your life, according to research published last year by Harvard University.
The side effects of going low carb
Severely restricting carbs, as in a keto diet, comes with its downsides since your body prefers using the macronutrient for energy.
“If you cut your main energy source you’re going to feel tired,” says Vavrek. Mood swings, constipation and troubles concentrating are also common complaints. Long term, you may experience hormonal changes if your carbs are too low.
Some people develop keto flu, when they adopt that style of eating. Symptoms typically arise in the first few days as your body gets accustomed to living without carbs. Common signs include headaches, nausea, fogginess, muscle cramping, and fatigue.
The bottom line on low-carb diets
The right diet is one that you can sustain long term, meaning low-carb isn’t necessarily better than any other plan.
Just be sure to take Vavrek’s advice before trying it out yourself.
“I wouldn’t do any extremes,” she says.
Melissa Matthews is the health writer at MensHealth.com and has written for Newsweek, Men’s Fitness, Inc.