Fad diets are extremely popular for losing weight.
They typically promise rapid weight loss and other health benefits, yet often have no scientific evidence supporting their use. In addition, they are often nutritionally unbalanced and ineffective over the long term.
However, there are some “fad” diets that have been found to produce weight loss in high-quality, controlled studies.
What’s more, these diets can be healthy, well-balanced and sustainable.
Here are eight “fad” diets that actually work.
1. Atkins Diet
The Atkins diet is the most famous low-carb weight loss diet in the world.
Created by cardiologist Robert Atkins in the early 1970s, the Atkins diet claims to produce rapid weight loss without hunger.
It consists of four stages, including an initial two-week Induction Phase that restricts carbs to 20 grams per day, while allowing unlimited amounts of protein and fat.
During this phase, your body begins converting fat into compounds called ketones and switches to using these as its main source of energy.
After this, the Atkins diet asks its followers to gradually add back their carbs in 5-gram increments in order to determine their “critical carbohydrate levels” for losing weight and maintaining the loss.
Studies that compared the Atkins diet to other diets have shown it to be at least as effective and frequently more effective for weight loss (, , , ).
In the famous A TO Z study, 311 overweight women followed the Atkins diet, the low-fat Ornish diet, the LEARN diet or the Zone diet for one year. The Atkins group lost more weight than any other group ().
Other controlled studies have shown similar results with low-carb diets based on Atkins principles, along with improvements in heart disease risk factors (, , , ).
You can read all about the Atkins diet here.
Summary: The Atkins diet is a high-protein, high-fat diet that restricts carbs and gradually adds them back in, based on personal tolerance. Studies have shown it is one of the most effective ways to lose weight.
2. South Beach Diet
Like Dr. Atkins, Dr. Arthur Agatston was a cardiologist interested in helping his patients lose weight sustainably and without going hungry.
He liked certain aspects of the Atkins diet, but was concerned that unrestricted use of saturated fat might increase the risk of heart disease.
Therefore, in the mid-1990s he created a lower-carb, lower-fat, high-protein diet called the South Beach Diet, named for the area in South Florida where he practiced medicine.
Although Stage 1 of the diet is low in carbs and very low in fat, the diet becomes less restrictive in Phases 2 and 3, which allow limited quantities of all types of unprocessed foods while keeping protein intake high.
The diet encourages a high intake of protein, because protein has been shown to burn more calories during digestion than carbs or fat ().
In addition, protein stimulates the release of hormones that suppress hunger and can help you feel full for hours (, ).
A large review of 24 studies found that high-protein, low-fat diets led to greater reductions in weight, fat and triglycerides and better retention of muscle mass than low-fat, standard-protein diets ().
There are many anecdotal reports of weight loss on the South Beach Diet, as well as a published 12-week study looking at its effects.
In this study, pre-diabetic adults dropped an average of 11 pounds (5.2 kg) and lost an average of 2 inches (5.1 cm) off their waists.
Additionally, they experienced a reduction in fasting insulin levels and an increase in cholecystokinin (CCK), a hormone that promotes fullness ().
Although the diet is nutritious overall, it requires an unwarranted drastic restriction of saturated fat and encourages the use of processed vegetable and seed oils, which may lead to all kinds of health problems.
You can learn more about the South Beach Diet by reading this article.
Summary: The South Beach Diet is a high-protein, lower-carb, lower-fat diet that has been shown to produce weight loss and reduce heart disease risk factors.
3. Vegan Diet
Vegan diets have become very popular among people looking to lose weight.
They’ve been criticized for being unbalanced and extreme because they contain no animal products. On the other hand, they have also been praised for being an ethical, healthy way of eating.
Importantly, vegan diets can be healthy or unhealthy, depending on the types of foods they contain. It’s unlikely that you can lose weight while eating large amounts of processed foods and beverages.
However, studies have shown that vegan diets based on whole foods can lead to weight loss and may reduce several risk factors for heart disease (, , ).
One six-month controlled study of 63 overweight adults compared the outcomes of five different diets. Those in the vegan group lost more than twice as much weight as those in any of the other groups ().
Moreover, longer studies have shown that vegan diets can yield impressive results.
In a two-year controlled study of 64 overweight older women, those who ate a vegan diet lost nearly four times as much weight compared to the low-fat diet group ().
To learn more about how to safely and sustainably lose weight on a vegan diet, read this article.
Summary: Vegan diets have been found to be effective for weight loss in both short-term and long-term studies. In addition, they may help protect heart health.
4. Ketogenic Diet
Although the ketogenic diet has been called a “fad” diet, there is no denying it can be very effective for losing weight.
It works by lowering levels of insulin and shifting your primary fuel source from sugar to ketones. These compounds are made from fatty acids, and your brain and other organs can burn them for energy.
When your body doesn’t have carbs to burn and switches to ketones, you’re in a state called ketosis.
However, unlike the Atkins and other low-carb diets, ketogenic diets don’t gradually increase their carbs. Instead, they keep carb intake very low to ensure followers stay in ketosis.
Indeed, ketogenic diets typically provide less than 50 grams of total carbs per day, and often less than 30.
A large analysis of 13 studies found that ketogenic diets not only boost the loss of weight and body fat, but may also reduce inflammatory markers and disease risk factors in those who are overweight or obese ().
In a controlled two-year study of 45 obese adults, those in the ketogenic group dropped 27.5 pounds (12.5 kg), and lost 29 inches (11.4 cm) from their waists, on average.
This was significantly more than the low-fat group, even though both groups were calorie-restricted ().
Moreover, even when calories aren’t intentionally restricted, ketogenic diets tend to reduce calorie intake. A recent review of several studies has suggested that this may be because ketones help suppress appetite ().
Read this article to find out more about how a ketogenic diet can help you lose weight.
Summary: Ketogenic diets often provide less than 30 grams of carbs per day. They’ve been shown to promote loss of weight and belly fat, and to lower the risk of disease in overweight and obese people.
5. Paleo Diet
The paleo diet, short for the paleolithic diet, is based on the diets that hunter-gatherers ate thousands of years ago.
Paleo has been classified as a fad diet because it restricts many foods, including dairy, legumes and grains. In addition, critics have pointed out that it isn’t practical or even possible to eat the same foods that our prehistoric ancestors did.
However, the paleo diet is a balanced, healthy way of eating that eliminates processed foods and encourages its followers to eat a wide variety of plant and animal foods.
In addition, studies suggest that the paleo diet may also help you lose weight and become healthier (, , ).
In one study, 70 obese older women followed either a paleo diet or a standard diet. After six months, the paleo group had lost significantly more weight and abdominal fat than the other group.
They also had a greater reduction in triglyceride levels in the blood ().
What’s more, this way of eating may promote the loss of visceral fat, the particularly dangerous type of fat found in your abdomen and liver that promotes insulin resistance and increases the risk of disease.
In a five-week study, 10 obese older women who ate a paleo diet lost 10 pounds (4.5 kg) and had a 49% reduction in liver fat, on average. In addition, the women experienced reductions in blood pressure, insulin, blood sugar and cholesterol ().
You can learn more about the paleo diet and how it can help you lose weight here.
Summary: The paleo diet is based on ancestral eating principles that focus on whole, unprocessed foods. Research suggests it may help you lose weight and improve your overall health.
6. The Zone Diet
The Zone diet was created in the mid-1990s by Dr. Barry Sears, a US-based biochemist.
It has been classified as a fad diet due to its premise that a strict ratio of protein, fat and carbs is required for optimal weight loss and overall health.
This eating plan specifies that your calorie intake should be made up of 30% lean protein, 30% healthy fat and 40% high-fiber carbs. In addition, these foods are to be consumed as a prescribed number of “blocks” at meals and snacks.
One of the ways the Zone diet is proposed to work is by reducing inflammation, which allows you to lose weight more easily.
Studies to date suggest the Zone diet can be effective for losing weight and reducing blood sugar, insulin resistance and inflammation (, , ).
In a controlled, six-week study of overweight adults, those who ate the Zone diet lost more weight and body fat than the low-fat group. They also reported a 44% reduction in fatigue, on average ().
In another study, 33 people followed one of four different diets. The Zone diet was shown to help participants lose the most fat, and to increase the ratio of anti-inflammatory omega-3 fatty acids to omega-6 fatty acids ().
You can learn more about the Zone diet by reading this article.
Summary: The Zone diet specifies a diet composed of 30% lean protein, 30% healthy fat and 40% high-fiber carbs. Research suggests it may help you lose weight and reduce inflammation.
7. The Dukan Diet
Looking at the initial stages of the Dukan Diet, it’s easy to see why it is often classified as a fad diet.
Developed by French doctor Pierre Dukan in the 1970s, the Dukan Diet consists of four stages. It starts with the Attack Phase, which consists almost entirely of unlimited lean-protein foods.
The rationale for this very high protein intake is that it will lead to rapid weight loss as a result of boosting metabolism and significantly decreasing appetite.
Other foods are added with each stage until the Stabilization Phase, where no foods are strictly off-limits, but high-protein foods and vegetables are encouraged. The final phase also requires that you eat only Attack Phase foods once a week.
As extreme as this diet seems, it does appear to produce weight loss.
Polish researchers assessed the diets of 51 women who followed the Dukan Diet for 8–10 weeks. The women lost an average of 33 pounds (15 kg) while consuming about 1,000 calories and 100 grams of protein per day ().
Although there isn’t much research on the Dukan Diet specifically, studies have found that similar high-protein diets may be effective for weight loss (, , ).
Indeed, a systematic review of 13 controlled studies found that high-protein, low-carb diets are more effective than low-fat diets for producing weight loss and reducing the risk factors for heart disease ().
If you are interested in learning more about the Dukan Diet, read this article.
Summary: The Dukan Diet begins with a nearly all-protein diet and allows other foods in its later stages. Like other high-protein, low-carb diets, it can promote rapid weight loss while controlling hunger.
8. The 5:2 Diet
The 5:2 diet, also called the fast diet, is a type of intermittent fasting known as alternate-day fasting.
On this diet, you eat normally for five days a week and restrict your calorie intake to 500–600 calories for two days each week, resulting in an overall calorie deficit that leads to weight loss.
The 5:2 diet is considered a form of modified alternate-day fasting. By contrast, some types of alternate-day fasting involve going without food for a full 24 hours.
The extremely low calorie allotment on the two “fast” days has led some to classify the 5:2 diet as a fad diet.
However, the evidence supporting the health benefits of alternate-day fasting is growing, and it seems to be a legitimate option for weight loss ().
Research suggests that alternate-day fasting doesn’t cause excessive calorie intake on eating days. This may be due to the release of peptide YY (PYY), a hormone that makes you feel full and helps you eat less ().
Importantly, alternate-day fasting hasn’t been shown to cause greater weight loss than standard diets containing the same number of calories.
However, several studies have found that both approaches can be effective for losing weight and belly fat (, ).
What’s more, although it isn’t possible to completely prevent loss of muscle while losing weight, alternate-day fasting seems to be superior for maintaining muscle mass when compared to conventional forms of calorie restriction (, ).
You can learn more about the 5:2 diet by reading this article.
Summary: The 5:2 diet is a form of alternate-day fasting that involves eating 500–600 calories two days a week, and eating normally otherwise. It’s been found effective for losing weight and fat while protecting against muscle loss.
The Bottom Line
Fad diets will always be popular, and new plans will continue to be created to address people’s desire to lose weight quickly.
Although many so-called fad diets are unbalanced and don’t live up to their claims, there are several that actually do.
However, just because a diet is effective for weight loss doesn’t mean it is sustainable long-term.
To achieve and maintain your weight loss goal, it’s important to find a healthy way of eating that you enjoy and can follow for life.