Weight loss is one of the most common health goals, but it’s also one of the most overwhelming. With so much information out there about the best weight loss programs, workouts and diets for losing weight, it’s hard to know where to start or what will work for you. 

That said, some people want to have a specific plan to follow that can help them achieve their goals. If you’re exploring different diets or eating styles that may work for you, dietitians Amy Gorin and Dr. Shayna Peter help break down the pros and cons of different diets based on research, and their experiences with clients in their own practices.

We’ve also investigated the pros and cons of paid weight loss programs, but here we are looking at diets that you can follow for free, or for the cost of a book or guide about the diet.

Foundations of a healthy diet for weight loss

When looking for a diet that will work for you, you need to consider various factors, including if it’s realistic for you to follow, if you like the foods involved and if the diet has any potential health benefits or risks you should be aware of. 

In general, Gorin and Dr. Peter say you should look for the following when considering a healthy diet plan:

It includes plenty of whole foods and balanced macro groups

“When I counsel people for weight loss or for healthy eating in general, I typically advise eating vegetables or fruit at every meal and adding a lean protein (for instance, tofu, beans, salmon or chicken breast), a healthy fat (such as avocado, olive oil, or olives) and a whole grain like brown rice or quinoa to every meal. This combination of food sticks with you for longer and provides a multitude of nutrients,” Gorin says. 

It’s sustainable 

“I like looking at weight loss as making long-lasting small lifestyle changes, versus doing sweeping changes that you might be less likely to stick to,” Gorin says. 

Whenever you are considering changing your diet, always consult your doctor and consider consulting with a dietitian or nutritionist before making a drastic change. “Don’t jump on whatever diet plan your friends are doing. Speak with a nutrition professional who can help you identify the eating plan that is most suitable for you. Go with a program that is sustainable, even if the weight loss is slower,” Dr. Peter says.

5 diets evaluated by dietitians 

Whole30 diet

Whole30 is a popular challenge developed by sports nutritionist Melissa Hartwig-Urban. It’s basically a form of the elimination diet, where you remove certain foods for a period of time that could be causing adverse medical symptoms, like a recurring upset stomach. Although it’s not technically marketed or meant for weight loss, some people do lose weight during the 30-day challenge. 

Pros

If you use a Whole30 challenge as a tool for identifying food sensitivities or foods that trigger negative symptoms, it could be helpful for you. “[Whole30] is a structured elimination diet similar to paleo and helpful for identifying food triggers,” Dr. Peter says.

Cons

“The diet is so restrictive — if you slip up even once and eat a bite of pizza or a spoonful of ice cream, you have to reset and start over on the diet. I haven’t found this type of unforgiving mentality to work with my clients,” Gorin says.

When it comes to weight loss, Whole30 is pretty restrictive and hard to follow, meaning the chances you’ll be able to stick to it are pretty low. Also, since Whole30 isn’t designed for weight loss, you can technically follow the plan and not lose any weight, if you aren’t also paying attention to portion sizes and macronutrient ratios.

Paleo diet

The Paleo diet is a style of eating that mimics what we think our cavemen ancestors followed — aka a hunter-gatherer style of eating. The main tenets of the diet involve eating fruits, veggies and meats mainly, and nixing dairy, grains, beans, wheat and some other foods. 

Pros

“[The Paleo diet] excludes processed foods, inflammatory foods such as grains, dairy, refined sugar, foods high in lectins. It can be very beneficial for reducing inflammation, especially in people who have autoimmune conditions,” says Dr. Peter. Some studies show that the diet can be helpful for weight loss (although there needs to be more research).

The Paleo diet requires you to cut out grains, which is a controversial topic in the nutrition world. Some say that the benefits of grains outweigh the potential negative effects, and that removing all grains is too restrictive. According to Peter, removing grains from your diet, “can enhance mineral absorption. Grains contain phytates, which can interfere with mineral absorption.” 

Cons

“Some research suggests that the eating style could lead to short-term improvements in waist circumference and fasting blood sugar, risk factors for chronic diseases. But there hasn’t been a lot of research on the diet, especially on its long-term benefits. For this reason, I don’t think it’s the best approach to weight loss, especially considering how restrictive it is,” Gorin says. 

Peter also points out that the Paleo diet can be tough to transition to, especially if you are used to the Standard American Diet. 

Keto diet

The Keto diet is one of the most popular (and controversial) diets today. It’s also one of the more extreme diets since it involves eating a huge amount of fat in comparison to other nutrient groups, and it almost completely cuts out carbs (like fruit and sweet potatoes) from your diet. The goal of the keto diet is to restrict carbs enough that your body goes into ketosis, which is a state where your body begins to burn fat instead of sugar for energy.

Pros

“Certain people may find this diet helpful. For instance, people with Type 2 diabetes could find a benefit — as some research shows that a higher protein and higher fat diet like the keto diet may help manage hunger levels. The diet could also help increase A1C levels,” Gorin says. 

Cons

“This is not a diet I’d recommend for most people. It is extremely difficult to follow, especially long-term. We also don’t have a clear picture of long-term benefits of weight loss,” Gorin says. 

Because of the restrictive nature of the diet, Gorin says you’re more prone to certain nutrient deficiencies, including fiber and sodium. One of the effects of the Keto diet is lower insulin levels, which plays an important role in how your body regulates sodium. Low-carb diets cause your body’s insulin levels to go down, which causes your body to flush excess water and sodium. 

That might sound harmless, but your body needs a proper balance of sodium to function. “In extreme cases, this [low sodium level] could lead to more severe side effects such as seizures, coma and death,” Gorin says.

Other people that Gorin says the diet will not work for is those with a history of disordered eating, people with kidney disease or a history of experiencing kidney stones and people with Type 1 diabetes.

Vegan diet

Whether followed for health or ethical reasons, a vegan diet is a popular diet that removes all animal products from the diet. This means the diet is made up of mainly fruits, vegetables, grains and beans and nixes meat, fish, eggs, dairy and any other food products that contain any ingredients that come from animals. 

Pros

“People who follow this type of diet see benefits in weight control, as well as a reduced risk for Type 2 diabetes and coronary heart disease,” Gorin says. 

Cons

“A balanced vegan diet can be challenging to follow, so make sure that you’re eating a variety of nutrients and getting ample protein. There are certain nutrients that are more difficult to get from a vegan diet, such as vitamin B12 and omega-3s, so you may want to consider taking certain supplements,” Gorin says. 

Peter adds that one challenge with veganism is getting enough amino acids. “Amino acids are the building blocks of proteins. Essential amino acids can only come from food and cannot be made by the body. Methionine is a common amino acid deficiency in vegans that is needed for brain and liver function,” Dr. Peter says. 

She also cautions that some vegans can end up eating more carbs than is beneficial, which can cause blood sugar and weight control issues for some people. “[Vegans] can also develop other nutritional deficiencies like choline, zinc, Iron, B12, vitamin D and chromium,” Dr. Peter says. 

Mediterranean diet

The Mediterranean diet is a style of eating that is based on the dietary habits of countries that border the Meditteranean Sea — most prominently Greece and Italy. At the time the diet was created, those countries experienced significantly lower levels of heart disease compared to other countries, like the United States. The diet emphasizes foods like fish, vegetables, fruit, nuts, beans and whole grains, with some smaller amounts of red meat and dairy.

Pros

“This is really more of a lifestyle than a diet, and I’d recommend it to pretty much anyone. There is much research to show that the Mediterranean diet can be helpful for health as well as weight loss,” Gorin says. 

Cons

Neither dietician cited any concerns over the diet since it is well-backed by research and is a favorite of many experts. One reason is because it’s more of a balanced lifestyle, instead of a restrictive diet that limits large food groups.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.