Weighty Matters: Consider the pros and cons of popular diets

The motivations to diet can be as varied as the number of diets available.

A 2024 survey conducted by the International Food Information Council found more than half of the 3,000 Americans questioned tried to follow a diet or eating pattern in the past year. The top reason cited was to feel better and have more energy. Others included losing weight, protecting long-term health and better managing a health condition.

There are more than three dozen recognized types of diets. Four of the most popular are plant-based, keto, intermittent fasting and paleo.

Which is right for you? Health and wellness professionals say there are pros and cons to consider.

Plant-Based Diet

Plant-based diets began to gain momentum in the 1970s, but it wasn’t until approximately four decades later that they truly became mainstream. Now, many chain restaurants have added vegan options, and supermarkets have expanded their selection of vegan processed foods.

There aren’t too many surprises with a plant-based diet. An individual consumes foods primarily — but not entirely — derived from plants, including vegetables, fruits, nuts, seeds, oils, whole grains, legumes and beans.

There are certainly many positives to the plant-based diet, but it isn’t perfect, according to board-certified nutritionist Dr. Peter Brukner.

“The plant-based diet has lots of fiber, vitamins and antioxidants,” says Brukner. “It can help lower chances of heart disease, diabetes and some cancers, too. It’s also good for losing weight because plant foods usually have few calories but many nutrients.”

But those who don’t plan well may miss out on necessary protein, vitamin B12, iron and omega-3s, Brukner says.

“Those are important for energy, muscle and complete health,” he says. “Without good planning, the plant-based diet can make it difficult for people to make sure they get everything their body needs.”

Akanksha Kulkarni, a registered dietician with Prowise Healthcare, says a more plant-focused diet is great for heart health and preventing or managing chronic diseases, including diabetes and hypertension.

“The plant-based diet can be a lifestyle, provided it is well-balanced perhaps with some supplementation,” she says.

Dietician and nutritionist Ria Hawle also believes plant-focused eating is more of a lifestyle than a temporary diet and says individuals can expect to lower their risks of heart disease and certain cancers.

“Some processed plant-based foods can be over-salted or lower in nutrients, but with the proper balance it can be highly sustainable,” she says. “A potential downside or challenge is that it can fall short in protein, B12, iron and omega-3s, but with a bit of planning these nutrients are manageable through food choices.”

Keto Diet

A staple of the diet scene for decades, the keto diet is a low-carb, high-fat diet with the goal of putting the body into a state of ketosis in which it burns fat rather than carbohydrates for fuel. The diet is often used by people who seek rapid weight loss, increased energy and improved blood sugar levels.

While some have been successful in achieving these goals, the keto diet is not a lifestyle change, according to Jonas Hansen, a wellness professional with Nerogan Health.

“It’s not a well-rounded or nutritious diet, and it’s not sustainable long-term,” he says. “It’s a good way for someone with a substantial amount of weight or who plans to undergo bariatric surgery to drop some weight quickly.”

Family nurse practitioner Monelle Burrus of Bend, Oregon-based Verve Health agrees.

“It’s restrictive and most are unable to maintain it over long periods, so it often becomes part of a short-term weight loss goal,” she says. “Many people find it effective because of the rapid weight loss, and some get increased mental clarity from ketones, but it cuts out fiber-rich food, which can harm gut health and its high-fat content, if unwatched, will increase cholesterol.”

Registered dietitian Matt Rogers encourages those on the keto diet to take nutritional supplements since the diet does put people at risk for a number of nutrient deficiencies.

“Supplements can help avoid nutrient deficiencies, and they can even help fight against problems like the ‘keto-flu’ which makes the person feel sick, fatigued or lethargic when the body starts ketosis,” says Rogers, who works for the Texas-based liquid vitamin company Tropical Oasis.

The diet does have some upside to it as Rogers notes that in addition to weight loss, some of the most common benefits are reduced inflammation, better brain health and lower cholesterol.

“Many experts also believe that a keto diet can help reduce symptoms and even risk factors for various diseases, ranging from epilepsy to heart disease and Alzheimer’s,” Rogers says.

Intermittent Fasting

Intermittent fasting is an eating plan that alternates between fasting and eating on a regular schedule. While most diets focus on what to eat, IF is all about when you eat.

The good news for those who opt for IF is that the diet does come with options. The most common method is 16 hours of fasting and eight hours of eating. There is also the “5:2 method” which entails eating normally for five days and drastically reducing calories for two days. There is also an “alternate-day method.

“The appeal of IF is that it is manageable for obese patients and enhances the action of insulin and decreasing inflammation,” Kulkarni says. “The cons are that is may be tough to follow the plan as intended, and some individuals may overconsume food when it is available.”

Hansen was quick to point out IF has gained popularity in recent years as a method to lose and maintain weight.

“The thought is that when you don’t eat immediately upon rising, your body uses fat as fuel until you have a meal,” he says. “Stopping eating by a certain point at night is also a good way to maintain weight loss, and it’s not that hard to do. You already fast while you sleep; the idea is to extend that time period.”

Sean Ormond, a pain management physician with Atlas Pain Specialist of Glendale, Ariz., says IF can be a lifestyle for those willing to commit.

“It’s a lifestyle for some,” he says. “IF can be a long-term choice for individuals who find it manageable, but it’s essential to be mindful of nutritional intake and avoid excessive calorie restriction.”

Paleo Diet

Known to many as the “caveman diet,” the paleo diet focuses on eating foods that would have been available to our Paleolithic ancestors. The main foods associated with the paleo diet include lean meats, fish, fruits, vegetables, nuts and seeds. The diet excludes processed foods, grains, dairy and legumes.

“The paleo diet is sort of just eating what early humans are assumed to have eaten,” Burrus says. “It prompts eating whole, nutrient-dense foods low in sugar that could lower inflammation. The problem is that they don’t have many grains, and without dairy, calcium intake could dwindle.”

Focusing on red meat can also lead to high saturated fat intake, she says.

“For some, it is sustainable, but may need to be adjusted so that nutrition remains balanced,” Burrus says.

Brukner says the paleo diet can help people lose weight and improve metabolic health, but the lack of grains and dairy can present a problem.

“Grains and dairy are good for fiber, calcium and some vitamins so without them, you might not get important nutrients,” he says.

Dr. Amanda Dee Richardson, the owner of the Texas-based Healing Hands Chiropractic, says the paleo diet can be both a lifestyle choice and “potential fad” due to its exclusions.

“It does focus on whole foods, lean meats and vegetables, which can enhance overall health, but it excludes grains, legumes and dairy, which may lead to nutrient gaps,” she says. “Paleo comes with its benefits when appropriately managed, but all four diets fall short and fail to offer a balanced nutrient intake needed for lasting health. The key is finding a diet that supports your health goals and lifestyle in a sustainable way.”