It’s easy to see the appeal of low-calorie diets if you’re trying to lose weight. Shedding pounds is a matter of basic math: If you burn more calories than you consume, you’ll lose weight. You could even drop pounds by eating mostly Twinkies, snack chips and sugary cereals, if you keep the calorie count low enough, as a university professor showed when he lost 27 pounds on the “convenience store diet.”
But while adhering to a low-calorie diet may help you drop pounds relatively quickly, it’s not sustainable for long-term weight loss or good for your overall health, experts say. People should only undertake a low-calorie diet under the supervision of a physician or a registered dietitian, says Angela Goscilo, a registered dietitian in the New York City area. The number of calories you need on a daily basis depends on your gender, age and level of physical activity. For example, a moderately active man between the ages of 31 and 50 needs between 2,400 and 2,600 calories daily, according to the Institute of Medicine. A woman in that age range who’s moderately active needs 2,000 calories a day, according to the institute. (Doing a walking workout or bicycling five days a week would qualify as moderate activity.)
What Is a Low-Calorie Diet?
A low-calorie diet typically ranges from 800 to about 1,500 calories daily, Goscilo says. A number of low-calorie diets recommend consuming 1,200 calories daily. There’s nothing magical about the number 1,200, Goscilo says. It just happens that 1,200 is the smallest number of calories the average person can consume without harming his or her health. However, few people are “average.” Everyone has a different size, shape and level of physical activity. The 2015-20 Dietary Guidelines for Americans, released in 2016 by top U.S. health officials, provide caloric intake levels that men and women need to maintain their respective weights. These guidelines state that women need from 1,800 to 2,400 calories each day to maintain their weights. The caloric range for men is higher, ranging from between 2,000 to 3,200 calories on a daily basis to maintain their weights.
[See: How to Make Healthful Dietary Changes Last a Lifetime.]
What Are Low-Calorie Foods?
There are different versions of low-calorie diets. For example, in 2010, Mark Haub, a professor of human nutrition at Kansas State University, dropped 27 pounds in two months by eating mostly Twinkies, snack chips and sugary cereals. Haub limited himself to less than 1,800 calories a day on the “convenience store diet.” Most low-calorie diets are very different, and recommend consuming foods that are low in calories and high in nutrients. Goscilo and Kimberly Gomer, a registered dietitian with Pritikin Longevity Center + Spa in Miami, say these are foods that would be part of a typical low-calorie diet:
Breakfast
— Oatmeal with fresh fruit and no added sugar
— One cup of coffee or tea
Lunch
— Sliced deli turkey breast on two slices of whole-grain bread
— One half-cup of carrots or a piece of fresh fruit, like a pear or an apple
— Water
Dinner
— A 3-ounce piece of baked or broiled salmon or flounder
— One cup of steamed broccoli, asparagus or other vegetables
— One cup of fat-free pudding
Snacks
— Air-popped popcorn
— Edamame
— Yogurt topped with fresh fruit
— Veggies with hummus
— Apples
— High-fiber crackers with low-fat cheese
How to Follow a Low-Calorie Diet
If you are going to follow a low-calorie diet, it’s best to do so under the supervision of your physician and/or in collaboration with a registered dietitian, Goscilo says. Medical and dietetic professionals can help guide you so you get the proper nutrients under a low-calorie regimen. You can use an app, like MyFitnessPal, which is free, to keep a daily diary of your food intake. Apps can also help you keep track of how many calories you burn daily, by inputting your activities.
How Long Does It Take to See Results?
It shouldn’t take long to see results from a low-calorie diet. Depending on how few calories you consume and your level of activity, you should lose a few pounds within a couple of weeks, and perhaps more, Gomer says. But Gomer and many other registered dietitians don’t recommend the low-calorie diet approach. Many people who follow such diets don’t feel satisfied or full, which can result in weight loss followed by weight gain, says Lise Gloede, a registered dietitian based in Arlington, Virginia.
[See: 10 Unusual Weight-Loss Tips That Actually Work.]
Dangers of Low-Calorie Diets
While many people may lose weight quickly from low-calorie regimens, the dropped pounds are often muscle and water in addition to some fat, Gloede says. “It’s not sustainable, and rapid weight regain occurs when the regimen ceases,” Gloede says. “It’s not recommended for long-term weight loss or maintenance.” A low-calorie regimen may also slow your metabolic rate in the long run, which would make it harder to lose weight. Low-calorie diets also don’t help people learn healthy eating habits, Gloede says. Gomer agrees. “Every low-calorie diet (of about 1,000 calories) will never be sustainable. In fact, it will cause more harm than good,” Gomer says. “The body will start sacrificing muscle, as it is more metabolically ‘expensive’ to maintain. So you lose weight, then break your diet and overeat.” When that happens, your body composition is compromised, and it will be harder to lose weight.
Extreme Low-Calorie Diets
Very low-calorie diets are typically defined as eating regimens that call for less than 800 calories a day, Gloede says. Some people may adopt an extreme low-calorie diet on their own to lose weight quickly, but it’s best to do so under a doctor’s supervision, she says. An extreme low-calorie diet usually involves consuming supplements, low-calorie shakes or meal replacements. You should also have frequent blood tests to measure such things as electrolyte levels, micronutrients, blood lipids, red and white blood cell counts, blood sugar levels and blood pressure. That’s because an extreme low-calorie regimen may not provide the nutrition the body needs and could negatively affect each of these measurements, Gloede says. “Those can go out of whack more easily because you’re doing something extreme,” Gloede says.
Dangers of Extreme Low-Calorie Diets
While you may lose weight in the short run on an extreme low-calorie diet, they’re risky for your health because the regimen probably won’t provide your body the calories and nutrients it needs to function normally, Gloede says. Most people typically need at least 1,200 calories daily, she says. “While many people may lose weight quickly from these types of regimens, often the weight (loss) is muscle and water in addition to some fat,” Gloede says. “It’s not sustainable and rapid weight regain happens when the regimen ceases.” Lindsay Malone, a clinical dietitian and manager of nutrition and health coaching at the Cleveland Clinic’s Center for Functional Medicine, agrees that a low-calorie approach has a potential downside. “If you’re eating a low-calorie diet but not getting enough protein, you could be dipping into your muscle stores for energy,” Malone says.
What Is Intermittent Fasting?
The intermittent fasting approach has become trendy among many dieters in recent years, boosted in popularity by books like “The Fast Diet: Lose Weight, Stay Healthy, and Live Longer with the Simple Secret of Intermittent Fasting” by Dr. Michael Mosley and Mimi Spencer, “The Obesity Code: Unlocking the Secrets of Weight Loss” by Dr. Jason Fung and “The 5:2 Diet: Feast for 5 Days, Fast for 2 Days to Lose Weight and Revitalize Your Health” by novelist/journalist Kate Harrison. One variation of intermittent fasting requires you to not eat for 16 hours of the day, and to consume all your food during an eight-hour time frame. For instance, under this approach, you’d eat only between noon and 8 p.m., with nothing in between. There are other intermittent fasting approaches, too. The 5:2 diet approach call for eating what you typically would five days of the week, and restricting your daily food intake to about 500 to 600 calories twice weekly. Another option is to fast for 24 hours once or twice weekly.
[See: Here’s What People Eat for Breakfast in 9 Other Countries.]
Is Intermittent Fasting Effective for Weight Loss?
Research suggests that adhering to an intermittent fasting regimen can be helpful for weight loss and reducing blood sugar levels, says Judy Matusky, a registered dietitian based in Ardmore, Pennsylvania. “There seems to be some body of evidence that circadian rhythm fasting, where meals are eaten within an eight- to 10-hour window, may be an effective alternative to a daily, reduced-calorie eating plan,” Matusky says. For example, a study published in June 2018 by the journal Nutrition and Healthy Aging suggests that restricting eating to an eight-hour window “produces mild caloric restriction and weight loss, without calorie counting. It may also offer clinical benefits by reducing blood pressure.” These approaches can be effective, says Dr. Jessica K. Bartfield, assistant professor in the bariatric and weight management center at Wake Forest Baptist Medical Center in Winston-Salem, North Carolina. She’s also an obesity medicine specialist. However, Bartfield cautions, intermittent fasting “isn’t necessarily for everybody.” If you’re considering going the intermittent fasting route, you should discuss it with a physician, she says.
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Low-Calorie Diets: a Basic Guide originally appeared on usnews.com
