Keep in mind that the Bulletproof Diet has several drawbacks.
Not Rooted in Science
The Bulletproof Diet claims to be based on solid scientific evidence, but the findings it relies upon are of poor quality and not applicable to most people.
However, cereal grains are often fortified with many important nutrients, and their consumption actually increases — not decreases — your intake of important nutrients (18).
And while it’s known that fiber from plant foods like rice decreases the digestibility of some nutrients, the effect is rather small and of no concern as long as you’re consuming a well-balanced diet (19).
Asprey also provides oversimplified views of nutrition and human physiology, suggesting that people shouldn’t regularly consume fruit since it contains sugar or that all dairy — except ghee — promotes inflammation and disease.
Can Be Expensive
The Bulletproof Diet can get expensive.
Asprey recommends organic produce and grass-fed meats, stating that they’re more nutritious and contain less pesticide residue than their conventional counterparts.
However, because these items are much more expensive than their conventional parts, not everyone may be able to afford them.
While organically grown produce tends to have lower pesticide residue and may contain greater levels of certain minerals and antioxidants than conventionally grown produce, the differences are probably insignificant to have any real health benefit (23, 24, 25, 26).
Requires Special Products
The Bulletproof line of branded products makes this diet even more expensive.
Many of the items in Asprey’s food spectrum that rank as Bulletproof are his own branded products.
It’s highly dubious for any person or company to claim that buying their expensive products will make your diet more successful (28).
Can Lead to Disordered Eating
Asprey’s continual classification of food as “toxic” or “Bulletproof” may lead people to form an unhealthy relationship with food.
Consequently, this can lead to an unhealthy obsession with eating so-called healthy foods, termed orthorexia nervosa.
Another study suggested that strict dieting was associated with the symptoms of an eating disorder and anxiety (30).
Summary The Bulletproof Diet has multiple drawbacks. It is not supported by research, can get expensive, requires buying branded products and may lead to disordered eating.
Source : https://www.healthline.com/nutrition/bulletproof-diet-review