There are many weight loss diets out there.

Axar.az reports that some focus on reducing your appetite, while others focus on restricting calories, carbs or fat. Since all of them claim to be “the best” diet, it can be hard to know which ones are worth trying. The truth is that no one diet is best for everyone, and what works for you may not work for someone else.

1. The Paleo Diet

The paleo diet claims that modern humans should eat the same foods that their hunter-gatherer ancestors ate the way humans were genetically designed to eat before agriculture developed.

The theory is that most modern diseases can be linked to the Western diet and the consumption of grains, dairy and processed foods.

While it’s debatable that this diet is comprised of the same foods your ancestors ate, it is linked to several impressive health benefits.

How it works: The paleo diet emphasizes whole foods, lean protein, vegetables, fruits, nuts and seeds, while avoiding processed foods, sugar, dairy and grains.

Some more flexible versions of the paleo diet also allow for dairy like cheese and butter, as well as tubers like potatoes and sweet potatoes.

Weight loss: Several studies have shown that the paleo diet can lead to significant weight loss and reduced waist size (1, 2, 3, 4).

In studies, paleo dieters have also been shown to automatically eat much fewer carbs, more protein and 300–900 fewer calories per day (1, 2, 3, 4).

Other benefits: The diet seems effective at reducing risk factors for heart disease, such as cholesterol, blood sugar, blood triglycerides and blood pressure (5, 6, 7).

The downside: The paleo diet eliminates whole grains, legumes and dairy. Therefore, it unnecessarily eliminates several healthy and nutritious food groups.

2. The Vegan Diet

The vegan diet was created by a group of vegetarians who also chose not to consume dairy, eggs or any other animal products.

The vegan way of life attempts to exclude all forms of animal exploitation and cruelty for ethical, environmental or health reasons.

How it works: Veganism is the strictest form of vegetarianism.

In addition to eliminating meat, it eliminates dairy, eggs and animal-derived products, such as gelatin, honey, albumin, whey, casein and some forms of vitamin D3.

Weight loss: A vegan diet seems to be very effective at helping people lose weight, often without counting calories. This may be explained by its very low fat and high fiber content, which makes you feel fuller for longer.

Vegan diets have consistently been linked with lower body weight and body mass index (BMI), compared to other diets (8, 9, 10, 11, 12).

One study showed that a vegan diet helped participants lose 9.3 lbs (4.2 kg) more than a control diet over 18 weeks. The vegan group was allowed to eat until fullness, but the control group had to restrict calories (13).

However, vegan diets are not more effective for weight loss than other diets when matched for calories (14).

Other benefits: Plant-based diets have been linked with a reduced risk of heart disease, type 2 diabetes and premature death (15, 16, 17, 18, 19).

Limiting processed meat may also reduce your risk of developing Alzheimer’s disease and dying from heart disease or cancer (20, 21, 22, 23, 24).

The downside: Vegan diets eliminate animal foods completely, so they may be low in several nutrients. This includes vitamin B12, vitamin D, iodine, iron, calcium, zinc and omega-3 fatty acids (25, 26, 27, 28, 29).

3. The Ultra Low-Fat Diet

An ultra low-fat diet restricts the consumption of fat to under 10% of consumed calories.

Generally, a low-fat diet provides around 30% of its calories as fat.

Many studies have shown that this diet is ineffective for weight loss in the long term.

Proponents of the ultra low-fat diet claim that traditional low-fat diets are not low-fat enough and fat intakes needs to stay under 10% of total calories to produce health benefits and weight loss.

How it works: An ultra low-fat diet contains 10% or fewer calories from fat. The diet is mostly plant-based and has a limited intake of animal products (66).

Therefore, it’s generally very high in carbs (80%) and low in protein (10%).

Weight loss: This diet has been shown to be very successful for weight loss among obese individuals. In one study, obese individuals lost an average of 140 lbs (63 kg) on an ultra low-fat diet termed the rice diet (67).

Another 8-week study with a diet containing 7–14% fat showed an average weight loss of 14.8 lbs (6.7 kg) (68).

Other benefits: Studies have shown that ultra low-fat diets can improve several risk factors for heart disease, including high blood pressure, high cholesterol and markers of inflammation (69, 70, 71, 72, 73, 74).

Surprisingly, this high-carb, low-fat diet can also lead to significant improvements in type 2 diabetics (75, 76, 77, 78).

Furthermore, it may slow the progression of multiple sclerosis, an autoimmune disease that affects the brain, spinal cord and optic nerves in the eyes (79, 80).

The downside: The fat restriction may cause problems in the long-term, as fat has many important roles in the body. These include helping build cell membranes and hormones and helping the body absorb fat-soluble vitamins.

Moreover, an ultra low-fat diet limits the intake of many healthy foods, lacks variety and is extremely hard to stick to.