The top 10 weight loss programs, according to science

With so many weight loss plans available, it can be challenging to know which one to choose — especially since there isn’t one diet that’s the best fit for everybody.

If you want to lose weight and improve your health — with a plan that works for you — you’ve come to the right place.

In this review, we rank the 10 best weight loss programs based on the scientific evidence supporting their effectiveness. We’ll also explore each plan’s pros and cons to help you decide which option is right for you.


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Which weight loss program is right for you?

There is strong evidence that many different types of diets can help people lose weight.

However, some diets may lead to more dramatic weight changes than others. Certain diet plans may also provide greater improvements in health markers — like blood sugar control and heart disease risk factors — compared to other eating patterns.

Finding a diet that you enjoy and can stick with is important, too. If you view your diet as a long-term healthy lifestyle change rather than a quick fix, you’re more likely to lose weight and keep it off.

We’ve ranked the most popular weight loss plans primarily by their effectiveness for weight loss, and secondarily for improvements in health markers, based on the strength of the evidence to date.

Each diet received a score on a scale of 1 to 5 for weight loss and health changes, for a combined overall score out of 10. Importantly, any rating system of this nature can involve some level of subjectivity, and the exact scores can of course be debated.

We’ve also provided a description of the diets, along with their advantages and disadvantages.

If you’re ready to lose weight and keep it off, read our detailed review of the top 10 weight loss programs to find out which one is best for you.


1. Keto or very low carb diet

keto-food

Our top pick for weight loss, improvement in health markers, and sustainability? A keto or very low carb diet.

Pros

  • Often more effective for losing weight than other diets
  • Suppresses appetite, leading to weight loss without deliberate calorie restriction or hunger
  • Significantly improves blood sugar control and other markers of metabolic health

Cons

  • More restrictive than some other diets, including a moderate low carb diet (see below)
  • May initially cause side effects, known as the keto flu
  • Requires medical supervision in people who take medications for diabetes or blood pressure

Rating

Weight loss score: 4.5/5
Health benefits score: 4.5/5
Overall score: 9/10

Keto diet basics

A ketogenic (keto) diet minimizes carbohydrate (carb) intake while allowing more generous amounts of protein and fat.

Carbohydrates are found in starches (bread, potatoes, pasta), sweets (cookies, cake), milk, and fruit, among other foods.

On a ketogenic diet, you reduce carbs to the point where your body stops using glucose as its primary energy source and instead uses mainly fat — either the fat you eat or your stored body fat. This fat-burning state is known as ketosis.

A keto diet emphasizes eating adequate protein (meat, fish, eggs, cheese, or tofu), adding fat such as butter or olive oil for flavor and fullness, and including above-ground vegetables at most meals. Nuts and small amounts of berries are sometimes included.

How many carbs can you eat and still get into or stay in ketosis? This varies from person to person.

However, in studies, ketogenic or very low carb diets typically provide less than 50 grams of total carbs per day.

Weight loss

In several reviews of studies testing low carb diets against low fat and other diets, low carb has been found as effective — and frequently more effective — for losing weight.

And when data from these trials are looked at individually, very low carb diets typically produce the most dramatic weight and fat loss — even when people are allowed to eat as much of the keto foods as they need to feel satisfied.

In one of these trials, overweight adults who followed a non-calorie-restricted keto diet lost 26 pounds (12 kilos) and 5.8% of their body fat within 24 weeks, whereas those who ate a calorie-restricted low fat diet lost 14 pounds (6.5 kilos) and 2.8% of their body fat.

More recent studies have also found that keto diets produce impressive weight loss.

One reason keto diets are so effective for losing weight is because they typically suppress appetite, causing people to naturally eat less without deliberately restricting calories.

Health benefits

Aside from weight loss, very low carb diets often provide metabolic health benefits.

Of the three macronutrients — protein, carbs, and fat — carbs raise blood sugar the most.

When people with type 2 diabetes eat very low carb diets, they typically experience profound improvements in blood sugar control and can quickly reduce or discontinue their diabetes medication.

Very low carb diets often reduce triglycerides and increase HDL cholesterol levels (changes that are considered beneficial) more than other diets.

They can also lower blood levels of small, dense LDL — the type of LDL with the strongest link to heart attack risk.
And they can be very effective for lowering blood pressure.

To learn more about losing weight and improving your health with a keto diet, read our complete beginner’s guide to ketogenic diets.


2. Low carb diet

Food recomended on low carb diet or ketogenic diet

Pros

  • As effective or more effective for losing weight compared to other diets
  • Less restrictive than a keto diet, with side effects such as keto flu less likely
  • Often significantly improves blood sugar control and other markers of metabolic health

Cons

  • Typically produces more gradual weight loss than keto or very low carb diets
  • May not provide as much appetite suppression as keto or very low carb diets
  • Requires medical supervision in people who take medications for diabetes or blood pressure

Rating

Weight loss score: 4/5
Health benefits score: 4.5/5
Overall score: 8.5/10

Low carb diet basics

A low carb diet provides about 50 to 130 grams of total carbs per day.

That’s more than a keto or very low carb diet, but considerably less than the estimated 200 to 300 grams of carbs most people eat every day.

A low carb diet includes all of the foods on a keto diet — meat, eggs, above-ground vegetables, fats, and berries — plus a few others that are slightly higher in carbs, such as fruits, carrots, and possibly small amounts of starchy foods like sweet potatoes.

Weight loss

In reviews of trials lasting between eight weeks and 24 months, researchers have concluded that low carb diets often lead to greater weight loss than low fat diets.

In several of those trials, people who ate non-calorie-restricted low carb diets lost more weight than those who ate calorie-restricted low fat diets.

In a 2014 trial, 148 people were assigned to eat less than 40 grams of carbohydrate per day, or a low fat diet. Although the low carb group ended up averaging about 100 grams of carbs per day, they lost about 12 pounds (5.3 kilos) — more than twice as much as those in the low fat diet group.

Some research suggests that following a low carb diet might even help keep people’s metabolism from slowing down during weight maintenance.

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Health benefits

Low carb diets also outperform low fat and other dietary interventions for lowering blood sugar levels in people with diabetes.

Additionally, low carb diets may be beneficial for reducing markers of heart disease risk, particularly triglycerides and blood pressure.

And results from a two-year trial suggest that losing weight via a low carb diet may help reduce the amount of plaque in the arteries of people with heart disease.

To learn more about how to follow a low carb diet, including tips for getting started, read our complete low carb diet for beginner’s guide.


3. Intermittent fasting

Pros

  • Typically as effective or more effective for weight loss compared to chronic calorie restriction
  • Does not restrict type or amount of food during eating windows
  • Reduces time spent preparing, eating, and cleaning up after meals

Cons

  • For some, it may be difficult to fast for several hours or eat few to no calories on alternate days
  • May cause some side effects
  • Requires medical supervision in people who take medications for diabetes or blood pressure

Rating

Weight loss score: 4/5
Health benefits score: 4/5
Overall score: 8/10

Intermittent fasting basics

Intermittent fasting involves going for extended periods without eating. It includes time-restricted eating (skipping one or two meals every day) and alternate-day fasting (eating normally one day and fasting or eating very few calories the next day).

Unlike other weight loss plans, intermittent fasting specifies when you eat rather than what you eat.

Weight loss

Reviews of studies exploring time-restricted eating and alternate-day fasting have shown that they are as effective or more effective than daily calorie restriction for losing fat and improving health markers.

One review of clinical trials found that while alternate-day fasting or chronic calorie restriction led to similar weight and fat loss, people who practiced alternate-day fasting retained more muscle mass than those who ate a low-calorie diet every day.

Health benefits

A 2019 review of trials found that intermittent fasting lowered blood sugar and increased insulin sensitivity compared to control diets.

In one trial, people with type 2 diabetes who practiced intermittent fasting for 12 months improved their blood sugar control as much as people who followed calorie-restricted diets.

One problem with intermittent fasting trials is that people are usually advised to eat whatever they want during non-fasting periods — which could include processed foods high in sugar and other refined carbs.

Regardless of how often you eat, getting adequate essential nutrition — especially protein — and limiting less nutritious foods is important for sustainable weight loss and overall health.

If you are going to practice intermittent fasting, choose nourishing, minimally processed foods whenever you eat.

To learn more about time-restricted eating and alternate-day fasting, read our intermittent fasting for beginners guide.


4. Mediterranean diet

Mediterranean diet

Learn how to do a keto diet