It’s no secret that a diet high in fat can cause trouble to the body, but new research has discovered that the brain can also get caught up in the mess. 

One of the ways the brain keeps prime performance is through the work of the immune cells. They bustle around the brain like scavengers, getting rid of damaged cells or infectious agents in the brain. 

These immune cells are important for healthy brain function, but when a diet is so high in fat as to cause obesity, they stop bustling and start eating the connections between neurons. 

Too much fat in the body seems to cause chronic inflammation, which triggers these immune cells to have an autoimmune response. They stop mopping up toxins and instead turn on their own healthy brain cells. The fallout from this includes a reduced capacity to learn as efficiently.

According to researcher and neuroscientist Dr Alexis M. Stranahan, immune cells ‘eating synapses is contributing to synapse loss and cognitive impairment in obesity.’

It’s a scary prospect, but the damage is completely reversible. Changing to a low-fat diet for two months can reverse the damage completely and restore healthy cognitive function.

The research was conducted using two groups of male mice. (Mice are commonly used in research for their  biological and genetic similarity to humans.) One group ate a diet that was 10% fat, the other group ate a diet that was 60% fat. The human version of these diets would be along the lines of a healthy diet versus a fast-food diet.

After eight weeks, the mice on the high-fat diet were fatter – no surprises there – but they were similar to the mice in the low-fat group in terms of brain changes and other physiological measures.

At 12 weeks, the differences between the groups started to show themselves. The high fat mice were obese and there was evidence of reduced brain function.

At this point, half the mice in the high fat group were then placed on the low-fat diet. After about two months, their weight returned to normal, but they had a larger fat pad than their peers, making them a little more vulnerable to weight gain in the future.

The mice that remained on the high fat diet continued to get fatter, and the scavenger cells and neurons in their brain continued to wither.

As explained by Stranahan, ‘Instead of doing garbage disposal, they are taking your mailbox, your front door, your kitchen sink and all the stuff that you need, and not doing their job of getting rid of trash.’

This research is compelling and is further evidence of the way the body and mind are deeply connected. The health of the body will ultimately affect the health of the mind. Obesity is stealing people from the lives they deserve to be living and from the people who love them. What we now know is that it is also stealing the capacity for people to learn and grow and reach their fullest potential. That affects all of us.

Food is meant to be fun, and it’s important to remember that the effect of fat on the brain uncovered by this research didn’t start to emerge until the point of obesity. In the same way that any unhealthy relationship – with people, work, exercise , anything – will cause problems, an unhealthy relationship will food will also bring us undone. The good news it that this is completely reversible. It’s not often we have the problem and the easy solution in one easy package. Thanks science.