The first time we noticed Jim from Accounts put butter in his coffee, we were a little perplexed. However, over the last couple of years, the increasing popularity of a “bulletproof” coffee has meant many cafes are now offering this as a drink.

The concept of a bulletproof coffee was popularised in the United States by a Silicon Valley computer programmer-turned health blogger, Dave Asprey, and refers to the addition of butter plus medium chained triglyceride(MCT) oil (or coconut oil) to coffee to help boost cognitive function, sports performance and promote weight loss.

Medium chaintriglycerides (MCTs) are found in small amounts in butter and make up two-thirds of the type of fat in coconut oil. There are four different MCTs and they are not easily stored in the body. Instead, they are broken down readily to be available as a fuel source.

These ketones are an alternative fuel source to glucose and don’t promote an insulin response the way glucose does. Therefore, consuming foods such as coconut oil and butter, that allow for a lower insulin level, will avoid blood sugar highs and lows that can lead to subsequent mood swings, energy crashes, and (in the long term) cholesterol and blood pressure abnormalities.

The pros

Focus and concentration is maintained as ketones are used as fuel by the brain. In fact, research shows that MCT scan improve cognitive function in people with dementia and in those with type 1 diabetes. Does this apply to the general population? Anecdotally yes, though I’ve not seen a scientific study to support it.

The ability of MCTs to be rapidly used as energy provides ready fuel for an athlete and the ability to burn fat is enhanced when MCTs are provided in the absence of glucose. While the jury is out as to their utility under high intensity exercise conditions, for the athlete that goes longer at a lower intensity, they are certainly useful.

In addition, providing fuel that doesn’t create the same oxidative damage that glucose does could potentially aid recovery from harder sessions. This increased fat-burning ability can, under certain circumstances, help burn more body fat and improve body composition.

Finally, as the same blood sugar lows aren’t experienced with dietary fat (as mentioned above), people won’t be drawn to foods they wouldn’t otherwise eat to help offset an energy crash and, thus, they may end up eating fewer (and better quality) calories overall.

The cons

One pitfall I’ve seen with clients is they supplement their diet with this drink, adding up to 400-500 additional calories per day, but do not compensate for it elsewhere. The problem with the modern diet is one of excess: excess fat, excess sugar, excess calories.

To add a bulletproof coffee to your diet and not consider the rest of your intake could have adverse implications for your metabolic health markers (such as cholesterol and blood sugar control) and body fat level. Another potential problem is that a bulletproof coffee takes the place of breakfast.

If you’re someone who enjoys an abundance of vegetables and protein at lunch and dinner then it’s likely not an issue. For some, though, breakfast is an important time to get nutrients such as minerals, vitamins, fibre and protein. The quality of the diet may reduce by cutting out this meal and enzyme and hormone function may (over the long term) be impaired.

This will have implications for the body’s metabolism, repair and recovery systems, the musculoskeletal systemand detoxification pathways. An inability to recover from exercise sessions, fatigue that can’t be shaken off, adverse changes to metabolic health markers and body fat gain are all signs that something is amiss.

This is also a good time to point out the notion that “fat doesn’t make you fat” or if you’re not losing weight you just need to “eat more fat” are both misnomers.

If you are trying to lose body fat and are stalling with your current dietary approach, drinking an additional 4 Tbsp of fat may not be the answer. I’m not saying that no one would benefit from this approach, but there are many other factors to consider before throwing a bulletproof coffee into the mix.

Fat may not cause the same hormone response that glucose does, which (as mentioned above) can create an environment for fat storage under certain conditions. However, the law of thermodynamics still stands: if you consume more calories than you expend, you will gain fat.