The Most Popular Diets Explained
by Amy Schlinger
No matter what your reason for wanting to eat a certain way—whether to bulk up, lose weight, manage blood sugar levels, or simply have your diet align with your personal beliefs and ethics—there are plenty of options to choose from.
From the ketogenic diet to intermittent fasting, you’ve probably heard many of these terms already. Of course, nutrition is highly personal, and what works well for someone else might not be the best fit for you—and vice-versa.
While starting up on a new diet is a decision that should always be made together with your doctor, there’s no harm in doing a little homework beforehand. So, to help you decode the most popular diets out there and find the one that might be right for you, we spoke with registered dieticians and nutrition experts about a few of the most talked-about diets of the moment—including their protocols, benefits, and drawbacks.
Intermittent fasting, also known as time-restricted eating or intermittent energy restriction is, in its simplest form, the alternation between scheduled fasting and non-fasting periods.
One of the most common ways you’ll hear of people incorporating this diet into their lifestyle is with the 16:8 method; you’ll often hear this referred to as “16 and eight.” The protocol is right there in the name; a 16-hour fasting period followed by an eight-hour window in which to eat.
Also popular but less common is alternate-day fasting—fasting every other day—or designating just one or two days a week for fasting.
“Within these methods, the same fasting protocol is used; it’s just the frequency and timing that varies,” explains Leslie Bonci, M.P.H., R.D., C.S.S.D., and sports dietician for the Kansas City Chiefs and Carnegie Mellon University athletics, and founder of Active Eating Advice.
“What is most appealing about intermittent fasting is that there is no need to change what you eat, but rather focus on when you eat,” Bonci says.
One of the main draws of intermittent fasting is its inherent reduction in caloric intake, which can promote weight loss. “If you take in fewer calories than you expend during the day, you will lose weight regardless of the method and protocol you use,” Bonci explains.
While more research is still needed, some studies have found that intermittent fasting could help support autophagy, the naturally occurring process where the body repairs damaged cells and generates new ones, while other research suggests it might help extend lifespan and lower the risk of cancer, heart disease, and obesity.
“Intermittent fasting can also be beneficial for diabetics who are trying to have better morning fasting blood glucose levels,” adds Bonci.
One of the biggest drawbacks of intermittent fasting, of course, is that there isn’t much wiggle room within its rigid framework. “This is why it’s important to plan ahead and make sure your fasting aligns with your schedule,” says Bonci. “It may be hard if an individual eats out a lot, works long shifts, or tends to work out at night.”
Also, since intermittent fasting focuses on when you eat but not what you eat, Bonci points out that it might not be the best choice for “an individual who already doesn’t eat well, as this protocol allows for eating habits to stay the same.”
Beyond the dietary component, veganism is a broader lifestyle that attempts to exclude all forms of animal exploitation and cruelty—for food, clothing, or any other purpose. So, as you’d expect, the vegan diet is devoid of all animal and animal-derived products, including meat, eggs, and dairy.
“People might choose to follow a vegan diet for a variety of reasons, ranging from ethics to environmental concerns, or simply out of a personal desire to improve their health,” explains Melanie Sulaver, M.S., R.D., C.D.N., C.I.S.S.N., a New York-based sports dietician and nutrition coach.
There is often some confusion, however, between being vegan versus being vegetarian. “Vegetarian diets are plant-centric and include vegan-style eating, but may include animal-derived products like dairy and eggs,” explains Sulaver.
Translation: Vegetarians tend to have a bit more flexibility, whereas vegans don’t. Put another way, “a vegan is a vegetarian, but a vegetarian is not necessarily a vegan,” she says.
So, ethical and environmental factors aside, why would someone limit their diet to exclude all animal and animal-adjacent food products? Well, the research makes a pretty compelling case. Studies have shown that adhering to a vegan diet has the potential to help with weight loss, lower blood sugar levels, and improve heart health. “This is likely related to the lower overall saturated fat intake from conventionally raised animal-derived products,” explains Sulaver.
This brings us to the drawbacks of veganism. Because the diet excludes many types of foods, it is especially easy to find yourself deficient in certain key vitamins and nutrients, like Omega-3 fatty acids and vitamin B12. “It’s important to understand that when we eliminate entire food groups—such as animal products—we need to be thoughtful about having a varied diet,” says Sulaver.
Similarly, by eliminating animal products, you’ll want to be extra conscious about making sure you’re consuming enough protein. Supplements, like plant-based protein powders, can really help you out here. That said, even on a vegan diet there are ways to find protein in the foods you’re able to eat. “You can get protein and vitamin B12 and iron from plant-based sources,” Sulaver says. “However, you’ll likely need to consume more of it due to how it’s absorbed.”
The Ketogenic Diet
The ketogenic diet, also known as the “keto” diet, is a low-carb, high-fat diet protocol. The goal of the diet is to enter into and maintain a metabolic state known as “ketosis,” where the body is turning to fat for fuel versus carbohydrates—its preferred source.
The keto diet requires you to get 60 to 80 percent of your macronutrient intake from fat, five to 10 percent from carbohydrates, and the remaining 10 to 30 percent from protein, explains Bonci.
Interestingly, this protocol was initially introduced to help control seizures in children with epilepsy, although scientists still don’t fully understand why it works. But that hasn’t stopped the masses from adopting the keto diet; for one, many people tend to experience weight loss relatively quickly after getting started.
“This is usually due to water loss from the carb restriction, but also some lean mass loss, too,” explains Bonci. “Plus, the high fat intake can make an individual feel fuller for longer, so he or she may eat less overall, which can cause a drop on the scale.”
While the keto diet requires a person to remain within specific macronutrient limits at all times, it has become easier and more convenient as keto-friendly products continue to enter the market.
That said, while the macronutrient quotas are relatively easy to follow, timing is another issue—and a potential drawback. The carbohydrate component, in particular, tends to trip people up. For example, even though you might be allowed a certain number of carbs in a given day, consuming too many in a single meal can kick the body out of ketosis. So, macronutrient distribution is something that needs to be considered at pretty much all times.
For athletes in particular, it is also important to note that the keto diet may not be the best choice for sports performance, specifically endurance-type sports that typically require carbs for fuel, explains Bonci, who adds that the keto diet may also be detrimental to bone health over the long term.
“This diet can also tend to be low in fiber, so it’s not great for the microbiome,” she says.
The DASH Diet
No, this is not a diet centered on fast food. (Sorry!) The name is actually an acronym for Dietary Approaches to Stop Hypertension.
“The diet is primarily designed to help manage blood pressure,” says Bonci, who notes that some studies have found this plan to be as effective as certain anti-hypertensive medications.
Unlike the paleo or keto diets, the DASH diet is very inclusive, with a particular emphasis on foods that are high in potassium, calcium, and magnesium, such as produce, low-fat dairy, omega-3-containing fish, whole grains, poultry, nuts, seeds, and beans. It is also a diet low in salt, fatty meats, sugar, and saturated fats.
The flexibility offered by the DASH diet is one of its biggest strengths. Generally speaking, it focuses a lot more on what to include versus what to exclude, explains Bonci. This is especially important when it comes to following any diet on a long-term basis, taking into account social situations like dinners as well as circumstances when food options are limited.
“Also, it is nutrient rich, so you don’t have to worry about not getting enough specific nutrients through food, nor do you have to restrict your eating at all,” Bonci says.
While there aren’t significant drawbacks associated with the DASH diet, Bonci points out that individuals who lose salt quickly—for example, through sweat during sports or workouts—may benefit from upping their sodium intake beyond what the diet protocol recommends.
The Paleo Diet
The paleo diet is a dietary plan modeled on the foods that might have been consumed during the Paleolithic era—hence the name.
“The main idea behind today’s paleo diet is that if humans were not able to consume a food thousands of years ago—before industrial agriculture, the domestication of animals, and modern food processing existed—then we should not consume it today, because the human body is not adapted to them,” explains Sulaver.
“Generally, followers of the paleo diet believe that the change from a hunting and gathering lifestyle to today’s modern diet is what has given rise to our numerous chronic diseases such as obesity, diabetes, and cardiovascular disease,” Sulaver says.
Essentially, following the paleo diet means sticking exclusively to foods that could have been obtained in the past by hunting and gathering. These include lean meats, fish, fruits, vegetables, nuts, and seeds.
“But in recent years, paleo proponents have suggested that individuals can introduce grass-fed dairy, like yogurt and other cultured options, and small amounts of ‘properly prepared’ legumes, meaning legumes that have been soaked or sprouted overnight,” Sulaver says.
Either way, one thing the paleo diet has going for it is its emphasis on consuming real, whole-food ingredients. No matter what, focusing on eating lean proteins, vegetables, fruits, nuts, seeds, and other healthy fats provides a massive improvement over the average Western diet, explains Sulaver. “For this reason, it is helpful in improving overall health, well-being, and managing chronic illness.”
Additionally, some research has shown that the paleo diet can help support weight loss, improve glucose intolerance, lower triglyceride levels, and manage appetite management.
Of course, just because certain foods weren’t readily available 2.5 million years ago, that doesn’t mean they’re inherently bad. “Evidence to support excluding these food groups isn’t very strong,” explains Sulaver. “In fact, most of us can improve the way we look, feel, and perform without eliminating these foods.”