We live in an age when fad diets and unhealthy trends are virtually everywhere, especially on social media, drawing in popular appeal with the hope and promise of helping you lose weight quickly. These diets typically fall into the category of low fat or low carb for rapid weight loss, and while it may sound as if pairing the two would help you shed pounds faster, be warned: Like oil and water, the two diets do not mix well.
Fats, carbohydrates and proteins are the three macronutrients we need to provide our body with energy to support normal bodily functions. While cutting out carbs or fats and focusing strictly on high-protein foods may work for weight loss in the short term, they are essentially deprivation diets that could have short- and long-term negative health impacts.
Why Low-Fat, Low-Carb Diets Don’t Work
Think of your macronutrients as a three-legged stool: People need all three in order to maintain a healthy, stable lifestyle. However, if you knock out one leg, it becomes harder to maintain your balance on the diet, and you’ll eventually fall off. If you knock out two, you’re left trying to balance on one leg — and, chances are, not for very long.
“When we cut out a complete food group or a complete nutrient, especially when (it’s) carbohydrates or fat, we are really limiting ourselves on a lot of great foods that have many benefits,” says Diana Guevara, a registered dietitian nutritionist with UTHealth Houston School of Public Health. “At a certain point, that willpower is just not going to hold up to reality.”
Not only can high-protein diets potentially increase the risk of kidney damage, it’s also an issue of missing out on a variety of other beneficial nutrients.
Protein comes from animal sources and plant-based sources. However, when you restrict yourself to a low-fat, low-carb diet, you’re eliminating nutrient-dense plant foods that are high in protein — such as beans, legumes, lentils, nuts and seeds — because they are good sources of healthy fats and fiber, which is a type of carb. This leaves you with only lean animal protein.
“It just seems like a sad diet to me,” Guevara says. “It’s not something I would recommend … for someone who is exploring living a healthy life.”
[READ: Which Diet Is Best? Plant-Based, Low-Fat vs. Animal-Based, Low-Carb]
Risk of Nutrient Deficiency With a Low-Fat, Low-Carb Diet
In addition, limiting fat intake also affects how your body absorbs other key nutrients that are integral to our overall health. Certain vitamins — namely vitamins A, D, E and K — are fat soluble. This means they require fat in order to be absorbed by the body..
These vitamins provide numerous benefits, including:
— Vitamin A supports healthy vision, immune system, reproduction and growth, as well as heart and lung function.
— Vitamin D promotes healthy bones, teeth, tissue and immunity and has been shown to reduce cancer cell growth and reduce inflammation. It may also play a role in our mental health, as vitamin D can influence depression, mood and quality of life, according to studies.
— Vitamin E supports vision and reproduction, as well as blood, brain and skin function.
— Vitamin K helps strengthen bones and prevents blood clots.
Without enough healthy fat in your diet, your body won’t be able to absorb those key vitamins.
Why You Need Carbs
Like fat, carbohydrates have historically been demonized, but it’s time to stop vilifying these macronutrients.
Carbs are your body’s main source of energy. When you consume carbs, they are broken down and converted into glucose to give your body energy to function. Healthy carbs — found in fruits, vegetables and whole grains — also provide you with fiber, which your body needs to support your digestive health.
Fiber is also important for your mental health and well-being. It nourishes the beneficial bacteria in our gut whose populations we are connected to a variety of health conditions and overall well-being. In fact, a 2021 study demonstrated that dietary fiber reduces symptoms of depression, and a 2021 study showed that consuming dietary fiber is associated with a reduced risk of anxiety and certain psychological disorders.
[SEE: What Are the Best Low-Carb Fruits?]
Other Diets to Consider
In certain situations, specifically patients who have undergone bariatric surgery, a low-fat, low-carb diet — such as the Dr. Now diet — may be recommended by a clinical team and overseen by a registered dietitian.
“People who have had bariatric surgery typically need to follow that kind of diet just so they can get their protein in at a low-calorie level, so it’s inherently a low-fat and low-carb diet,” says Audra Wilson, a registered dietitian and outpatient bariatric dietitian at Northwestern Medicine Delnor Hospital in Geneva, Illinois. But otherwise, she doesn’t recommend diets like this.
Instead of a low-fat, low-carb diet or any other restrictive diet for weight loss, experts encourage people to opt for eating patterns that are well-balanced and emphasize eating a variety of whole, nutritious foods.
“If you’re going on a diet, you’re going to get off a diet,” Wilson says. “I would rather encourage long-term, small changes to diet and lifestyle that can lead to better health and weight management over time.”
Programs like WeightWatchers, which ranked No. 1 in Best Weight Loss Diets in U.S. News’ 2023 Best Diets, can provide people with a structured plan to eat healthy for overall well-being. It focuses on eating a variety of healthy fats, proteins and fibers without limiting any food or food group.
Alternatively, Guevara and Wilson recommend the Mediterranean diet and DASH diet, which are ranked No. 1 and No. 2, respectively, in U.S. News’ 2023 Best Diets Overall and Best Diets for Healthy Eating.
Although neither diet is designed for weight loss, both eating patterns emphasize vegetables, fruits, whole grains, healthy fats, nuts, legumes, low-fat dairy and lean protein sources. These types of foods can provide high-quality, satiating fats and carbs in moderate amounts that, when paired with a healthy and active lifestyle, can promote weight loss.
Ultimately, for most people whose goal is to live a healthy life, maintain weight and prevent chronic diseases, experts don’t recommend highly restrictive diets, like a low-fat, low-carb diet.
“As a dietitian, our mantra is ‘All foods fit in a healthy diet,'” Wilson says. “There are no foods I would tell a patient not to eat. I would try to avoid those extreme words of ‘always’ and ‘never’ when you’re approaching your diet.”
Wilson encourages people to work with a registered dietitian who can help develop an eating plan that is highly nutritious and well-balanced to reach their health goals. “Let’s build something that has some balance, that you can sustain long term and that you like and enjoy because food should be enjoyed,” she adds.
More from U.S. News
What Foods Are Good for Your Liver?
The Best Mediterranean Diet Recipes
Healthy Carbs to Eat on a Diet
Are Low-Fat Low-Carb Diets Compatible? originally appeared on usnews.com
Update 06/16/23: The story was previously published at an earlier date and has been updated with new information.
