Less Weight, More Brains?


You can probably name a dozen reasons why being obese is bad for a person’s health. Well get ready to add one more. Aside from lowering your blood pressure, risk of a stroke, and chance of developing diabetes, losing weight can also aid your mind.

“I think weight loss, if it is done rightly, improves the memory and all the brain functions,” says Amari Medical Chief Medical Director Dr. J. Shah, who specializes in medical weight loss.

What the Studies Are Saying

It has already been pretty well established that obesity can impair cognition. A study from Northwestern University found that for every one-point increase in the subject’s BMI (all of the subjects were post-menopausal women), her score on a memory test dropped one point. That’s out of 100 points possible. Even the phrase “fathead” comes from the reduced cognitive abilities of obese individuals, according to Dr. Shah.

What is coming to light now is that this impairment may be reversible. A recent study from Umea University in Sweden found that, in a group of overweight post-menopausal women, those who shed some pounds were better at storing and recalling memories than those who stayed the same weight. Another study from Kent University in 2010 found that people who underwent bariatric surgery showed improved memory and concentration 12-weeks post-surgery. Prior to their procedures, the participants overall were found to have slightly impaired cognitive function. After surgery, they fell in the normal range.

How Weight Loss Improves Memory

There are many different theories concerning how weight affects brain function. Some researchers blame inflammation brought on by cytokines (hormones released by a certain type of fat), while others fault altered blood flow. Dr. Shah has a different explanation. When people diet, they generally take in less glucose than their bodies need for energy. So their bodies switch to using compounds called ketones as fuel. Dr. Shah says that these ketones are better food for our brains than sugar, which may contribute to improved cognitive function during weight loss. However, for most people, that heightened ketone presence disappears once they stop losing weight.

No Weight to Lose? No Problem.

Not everyone has pounds to spare. Luckily, healthy weight individuals might benefit from these findings as well. Dr. Shah says that it’s all about fueling your brain. “You don’t need carbohydrates to survive. You need the protein and the fat,” says Dr. Shah. “And good fat, I’ll say that, not the saturated fat.”

For some people, that may mean looking into a ketogenic diet, which consists of low carbs and about three times as much fat as protein. This eating plan is designed to increase the presence of those brain-fueling ketones (and lower sugar intake). However, this diet can make people feel a little funky at first and, if done wrong, can create other health problems. So consult your doctor before you give it a go. Ideally, improved health is the main purpose of any diet and it’s important to keep that in mind. Still, we won’t blame you if an extra dose of brainpower is a welcome side effect.


Kerwin DR et al. “The cross-sectional relationship between body mass index, waist-hip ratio, and cognitive performance in postmenopausal women enrolled in the Women”s Health Initiative”

Pettersson A et al. “Diet-induced weight loss improves episodic memory and alters brain activity in overweight postmenopausal women”
Gunstad J et al. “Improved memory function 12 weeks after bariatric surgery”