What Is the Bulletproof Diet?

Among the countless diets to choose from, the Bulletproof diet has gained increasing attention. The diet, best known for its namesake Bulletproof coffee, was created in 2014 as a new approach to quickly lose one pound a day.

Shot of a low carb high fat breakfast

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The Bulletproof diet shares some similarities with the keto diet and Atkins diet – the original high protein and high fat diet program. The main difference is that the Bulletproof diet is more restrictive, limiting certain major food groups such as most grains, beans and certain proteins like chicken, turkey and most fish.

“It is common for people to be enticed by the latest quick-fixes for weight loss,” says Ruth Lahmayer Chipps, a registered dietitian with Lahmayer & Associates in southern Minnesota. “What we know is that there are no easy answers for losing weight and most importantly, sustaining the weight loss. It takes a healthy lifestyle, balancing food intake with activity, to maintain a healthy weight.”

What Is the Bulletproof Diet?

Developed by technology entrepreneur David Asprey, the Bulletproof diet is best known for claiming rapid weight loss. Asprey weighed up to 300 pounds by his mid 20s and was not able to lose weight through existing diets. In his best-selling book, “The Bulletproof Diet,” Asprey describes his weight-loss journey and his discovery of a new immune approach to weight loss. The diet claims to allow weight loss without calorie counting or weighing food. It also claims to boost energy and willpower, increase cognitive function and mental performance, increase nutrient stores and strengthen immune system function.

The centerpiece of the diet is drinking Bulletproof coffee as a substitute for breakfast. The drink combines coffee with grass-fed unsalted butter and medium-chain triglyceride (MCT) oil, typically from coconut oil. The ingredients are mixed together and served hot like a creamy latte. The drink is promoted for its ability to prevent hunger and provide long-lasting energy and better mental focus.

In his book, Asprey says that, “eating carbs in the morning will set people up for an energy spike and crash along with food cravings throughout the entire day.” He suggests drinking Bulletproof coffee instead of eating a usual breakfast. “See how long it takes you to want food. For most people, it turns off the desire for food for at least five to six hours.”

In contrast, other diet experts warn against cutting out carbohydrates from eating plans.

“Carbohydrates get a bad rap,” says board-certified dietitian Roxana Ehsani, who is based in Miami. “They (carbohydrates) are an essential food group to consume that are rich in vitamins, minerals, dietary fiber and antioxidants – and found in some of our healthiest foods like fruits, vegetables, whole grains, beans, lentils and in some dairy products like milk and yogurt.”

How Does the Bulletproof Diet Work?

The Bulletproof diet focuses on eating keto foods that are high in fat and low in carbs for five to six days a week then having one to two carbohydrate days that might be tied to high-intensity exercise. A high carb day might be 50 grams of total carbs.

A core part of the diet is intermittent fasting – which means only eating during a certain number of hours each day. This could mean skipping breakfast and having lunch as your first meal and then eating dinner and fasting the remainder of the night. The goal of intermittent fasting is to fuel the body’s energy by burning fat stores and to lose extra weight. The other benefit of intermittent fasting is called metabolic switching. This happens when the body, after hours without food, exhausts its blood sugar stores and switches over to burning fat.

The goal of the diet plan is to eat very few carbs to reach ketosis – a metabolic state where the body burns fat and ketones instead of carbs and sugar for fuel. Ketones are chemicals in the liver produced when there’s not enough insulin in the body to turn sugar into energy.

Another goal of the diet is to reduce inflammation, so the diet recommends limiting certain foods that are known for causing inflammation like fried foods, sodas, processed meats and alcohol.

The Bulletproof diet classifies foods on a spectrum of three categories:

  • Green or “bulletproof” foods can be eaten any time except during fasting.
  • Yellow or “suspect” foods should be limited.
  • Red or “toxic” foods should be avoided.

Under this classification, butternut and winter squash, carrots, hummus, peanuts and eggs are all suspect foods. Chicken and turkey – which are mainstays in most diets – are also included in the suspect category. Poultry is okay a few times a week, but not as healthy as grass-fed meats because poultry fats are high in omega-6 fats, according to Asprey.

While omega-6 fats can be beneficial to lower cholesterol and improve insulin sensitivity, high levels of omega-6 fats are also linked to inflammation and sometimes blood clotting. The Bulletproof diet also recommends against broiling, barbequing, stir-frying and microwaving meat because it claims some proteins and fats in certain foods may be damaged during the cooking process.

Soy milk, corn, rice, beans, raw kale, raw spinach, raisings, honeydew and cheese are classified as toxic. Asprey revealed in his book that the classification system is based on the inflammatory properties of each food.

Some examples of foods to eat and to avoid are listed below with the full food guide available here.

Bulletproof Foods to Eat


  • Avocado, blueberries, blackberries, coconuts, cranberries, grapefruits, pineapples, strawberries.

Nuts, Seeds and Legumes

  • Almonds, cashews, chestnuts, coconut, coconut flour, hazelnuts, raw pistachios, walnuts, sunflower seeds.

Oils and Fats

  • Avocado oil, butter, dark chocolate, cacao butter, coconut oil, fish oil, ghee, egg yolks, medium triglyceride (MCT) oil.


  • Collagen, grass-fed beef, haddock, sardines, wild-caught fish.


  • Asparagus, avocado, broccoli, Brussels sprouts, cauliflower, celery, cucumber, cooked kale, spinach, zucchini.

Bulletproof Foods to Avoid


  • Dried fruit, canned fruit, honeydew, jelly and raisins.

Processed Meats

  • Bacon, canned meats, hot dogs and sausages.

Refined Carbs

  • Packaged snacks, pasta, pastries and white bread.

What to Know About the Bulletproof Diet

The restrictive nature of the diet has raised alarms from some nutrition experts. “A healthy eating program includes a balance of food groups and should not restrict or condemn individual foods,” says Chipps.

Consuming just coffee that contains butter on an empty stomach without consuming any other food will give you a false sense of energy from the caffeine, says Ehsani. “You might get a spike from the caffeine, but not giving yourself carbohydrates or a source of protein won’t leave you satisfied for long and isn’t feeding your brain.”

In addition to Bulletproof coffee, there is an entire line of Bulletproof products. The product line ranges from MCT oil, grass-fed ghee and an entire line of supplements with collagen and magnesium for sleep, stress relief and other benefits. Products cost anywhere from $36.99 for stress relief collagen protein to $132 for brain octane MCT oil.

Some nutrition experts have expressed caution around a diet plan that requires purchasing branded products. “Alarm bells should go off any time someone claims that you should buy their expensive products for your diet,” Chipps says. “Especially when the products come with miracle promises like Unfair Advantage, which claims to help grow new mitochondria – the energy powerhouses of the cells.” Chipps thinks the product is quite suspect in its claims to grow mitochondria.

The diet recommends adopting organic foods into daily meals. While organic foods are recommended when they’re available, they also come with higher price tags – that usually do not fall in the average American’s food budget.

Bulletproof Diet: Does It Work?

Can any diet help people lose one pound a day? According to the Centers for Disease Control and Prevention, people who lose weight gradually and steadily – about 1 to 2 pounds a week – are usually more successful in the long run. Most weight that’s lost in rapid weight loss efforts is typically what’s known as water weight.

“Quick weight loss generally encompasses fluid loss and may show results on the scale but the amount of actual body fat that is lost is often limited,” Chipps says. “Losing weight requires a consistent focus on reducing total calorie intake while increasing physical activity.”

Modest weight loss of 5% to 10% of your total body weight is likely to produce health benefits, says the CDC. Weight loss will lead to improvements in blood pressure, cholesterol levels and blood sugars.

Like many diets, there is no rigorous research examining the benefits of the Bulletproof diet and its inflammatory approach to weight loss. Even the keto diet, which was created in 1924 at the Mayo Clinic for children with severe epilepsy lacks long-term studies on its overall impact on weight loss.

Each individual needs to evaluate whether the Bulletproof diet is a good fit for them. Ehsani’s recommendation: “If you are looking for help in choosing the best diet for your individual needs, work with a nutrition expert who will help you find a healthy balanced diet that fits your unique health needs and wellness goals.”