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Weight loss

Most people can lose weight if they restrict the number of calories consumed and increase physical activity levels. To lose 1 to 1.5 pounds (0.5 to 0.7 kilogram) a week, you need to reduce your daily calories by 500 to 750 calories.

Low-carb diets, especially very low-carb diets, may lead to greater short-term weight loss than do low-fat diets. But most studies have found that at 12 or 24 months, the benefits of a low-carb diet are not very large. A 2015 review found that higher protein, low-carbohydrate diets may offer a slight advantage in terms of weight loss and loss of fat mass compared with a normal protein diet.

Cutting calories and carbs may not be the only reason for the weight loss. Some studies show that you may shed some weight because the extra protein and fat keeps you feeling full longer, which helps you eat less.

Other health benefits

Low-carb diets may help prevent or improve serious health conditions, such as metabolic syndrome, diabetes, high blood pressure and cardiovascular disease. In fact, almost any diet that helps you shed excess weight can reduce or even reverse risk factors for cardiovascular disease and diabetes. Most weight-loss diets — not just low-carb diets — may improve blood cholesterol or blood sugar levels, at least temporarily.

Low-carb diets may improve high-density lipoprotein (HDL) cholesterol and triglyceride values slightly more than do moderate-carb diets. That may be due not only to how many carbs you eat but also to the quality of your other food choices. Lean protein (fish, poultry, legumes), healthy fats (monounsaturated and polyunsaturated) and unprocessed carbs — such as whole grains, legumes, vegetables, fruits and low-fat dairy products — are generally healthier choices.

A report from the American Heart Association, the American College of Cardiology and the Obesity Society concluded that there isn't enough evidence to say whether most low-carbohydrate diets provide heart-healthy benefits.

Risks

If you suddenly and drastically cut carbs, you may experience a variety of temporary health effects, including:

  • Headache
  • Bad breath
  • Weakness
  • Muscle cramps
  • Fatigue
  • Skin rash
  • Constipation or diarrhea

In addition, some diets restrict carbohydrate intake so much that in the long term they can result in vitamin or mineral deficiencies, bone loss and gastrointestinal disturbances and may increase risks of various chronic diseases.

Because low-carb diets may not provide necessary nutrients, these diets aren't recommended as a method of weight loss for preteens and high schoolers. Their growing bodies need the nutrients found in whole grains, fruits and vegetables.

Severely restricting carbohydrates to less than 0.7 ounces (20 grams) a day can result in a process called ketosis. Ketosis occurs when you don't have enough sugar (glucose) for energy, so your body breaks down stored fat, causing ketones to build up in your body. Side effects from ketosis can include nausea, headache, mental and physical fatigue, and bad breath.

It's not clear what kind of possible long-term health risks a low-carb diet may pose because most research studies have lasted less than a year. Some health experts believe that if you eat large amounts of fat and protein from animal sources, your risk of heart disease or certain cancers may actually increase.

If you follow a low-carbohydrate diet that's higher in fat and possibly higher in protein, it's important to choose foods with healthy unsaturated fats and healthy proteins. Limit foods containing saturated and trans fats, such as meat, high-fat dairy products, and processed crackers and pastries.

Aug. 29, 2017 See more In-depth