If you're struggling to pick the right diet, you've probably heard about the low-carb vs. low-fat diet debate that never seems to stop. After all, both eating plans have been linked to the possibility of weight loss as well as prevention of serious health problems. So it's only natural that people following one diet or the other would start to claim their preferred side was "better." Let's get the short answer out of the way: Science has not definitively shown that either a low-carb or a low-fat diet is the "better" choice for the general public — for weight loss or other health benefits. Instead, finding the best diet for you depends heavily on your individual dietary needs — and that's where we delve into the long answer.
A February 2018 study found that cutting carbs or forgoing fats shaves off extra weight in the same proportion. The research, published in JAMA, analyzed hundreds of participants instructed to follow either a low-carb or low-fat diet for a year. On average, participants lost about 13 pounds afterward, but there was some variability; some folks dropped about 60 pounds and others gained 20. Along with not finding a clear "winner," the study also did not find that a person's insulin levels or genetics played a role in his or her success on either specific diet.
"We've all heard stories of a friend who went on one diet — it worked great — and then another friend tried the same diet, and it didn't work at all," said lead author Christopher Gardner, PhD, in a press release. "It's because we're all very different, and we're just starting to understand the reasons for this diversity. Maybe we shouldn't be asking what's the best diet, but what's the best diet for whom?" Dr. Gardner emphasized that it was key that both diets in the study were "healthy" diets. Remember: Always talk to your doctor before starting any kind of new diet, especially if you have any health conditions such as diabetes or heart disease.
What is a healthy low-carb diet?
The most basic definition of a low-carb diet is that it limits carbohydrates — found in grains, starchy vegetables like potatoes, and fruits — and emphasizes foods high in protein and fat. Though most people follow a low-carb diet with the intent of losing weight, some people that try it out to attempt to cut their risk for type 2 diabetes and metabolic syndrome. Generally, healthy low-carb diets emphasize lean protein — such as fish, poultry, and legumes — and healthy fats — such as avocados, nuts, and seeds. Some unprocessed carbs — such as whole grains, vegetables, and fruits — may also be included, depending on how restrictive the low-carb diet is for a specific person. It's worth noting that just because a food is low-carb doesn't necessarily mean that it's healthy; for example, animal lard is low-carb. It's also important to remember that healthy low-carb does not mean no-carb; some extremely restrictive low-carb diets might not provide necessary nutrients and could lead to serious health problems.
What is a healthy low-fat diet?
A low-fat diet involves limiting total fat and saturated fat, followed not only by people who want to lose weight but also those who have trouble digesting fat. People following low-fat diets are often recommended to forgo higher-fat dairy products, such as whole milk, whole milk cheeses, cheesy sauces, sour cream, and whipped cream. Unsurprisingly, sweet creamy products like ice cream often get slashed. A healthy low-fat diet emphasizes many fruits, vegetables, and legumes, as well as low-fat dairy options and low-fat cooking methods for meat, such as grilling. Some very low-fat diets may even restrict some healthy fats — such as oils, nuts, and seeds. Certain lean cuts of meat that contain fat may also be banned in some cases, depending on the individual's specific needs. It's worth remembering that — much like with a low-carb diet — just because a food is low-fat doesn't necessarily mean that it's good for you; for instance, soda is low-fat and few people would ever call that healthy.
What do healthy low-carb and healthy low-fat diets have in common?
Gardner said the main takeaway from his recent study is that the core strategy to losing weight with a low-carb or a low-fat diet is not so different after all. Indeed, both eating plans have many important similarities; both emphasize consuming less sugar and refined flour. Eating whole foods rather than those that have been processed is crucial. And of course, eating as many vegetables as possible is vital to any healthy diet you and your doctor choose. "On both sides, we heard from people who had lost the most weight that we had helped them change their relationship to food, and that now they were more thoughtful about how they ate," said Gardner. Hard to argue with that!
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