Dave Asprey, a tech millionaire and an author of the bulletproof diet book, claims that his butter-rich and high-fat diet coffee will enhance the dieters' body and boost their brain. However, scientists disagree and note that there is no truth in his claims.

Asprey has suffered from weight gain although he was successful and he has tried various diets but nothing worked for him. Asprey then tried to assess himself and map out his own diet system in order to find what fits him best so he could drop the extra pounds.

He was then able to discover foods and drinks that were good for him both in physical and mental aspects. The diet is said to be high in saturated fat and no fruits are allowed.

His discovery dates back in 2002 while he was in Tibet when he drank yak butter tea then he started to feel amazing. He said in his blog, "It's the only thing that keeps you going at altitude, and the locals drink up to 40 glasses a day!"

And so the Bulletproof coffee was born, yak butter plus coffee that is.

In Asprey's blog, he writes: "countless thousands of research papers online, [spent] more than 10 years working with some of the world's top health and nutrition researchers, [and read] over 150 nutrition books. This diet will not only make you stronger and leaner but it will also "upgrade" your brain and reduce your risks of cancer, heart disease, stroke, diabetes, and Alzheimer's."

He also added that he is living proof as his anti-aging physician told him that he is in the lowest percentile for diabetes, heart disease, and cancer as compared to how his body was ten years ago. The 41-year-old boasts that he has lower triglyceride levels and his IQ has been increased to 20 points.

However, scientists all over the world contest his claim and say that a diet low in saturated fat is more recommendable.  According to the American Heart Association, "Decades of sound science has proven it can raise your 'bad' cholesterol and put you at higher risk for heart disease."

The book has also been discredited and professor and scientists stand firm saying it is not a valid diet. According to Dr Celeste Naude from the Centre for Evidence-based Health Care at Stellenbosch University in South Africa, the diet is overly simplistic as it focuses on a single nutrient, which in this case is the saturated fat. She adds that it is not enough to actually measure its health benefits.

The book is still set to be out on December 2 this year.