NEW YORK (CBSNewYork) — A new study claims that your weight matters when it comes to the risk of dementia, but it’s contrary to what you might think.

A new study out of London found that those with more body fat are less likely to develop dementia in old age.

As CBS2’s Meg Baker reported, this may come as a surprise to some people after being told that eating well and staying fit are the keys to a long, healthy life.

“It contradicts a lot of studies from before where it’s finding people overweight have a decreased risk of dementia,” Daniel Yadegar, MD, Weill Cornell Medical College, explained.

A study of two million people found that those who are underweight versus overweight are more likely to develop dementia.

Dr. Yadegar warned people not to take the study at face value.

“It’s definitely not a carte blanche to go to the nearest fast food restaurant and eat what you want,” Dr. Yadegar said.

Nutritionist Carolyn Brown, MS, RD, said that when you eat, it’s important to feed more than just the waist line. She suggested choosing brain boosting foods.

“We are loving tumeric right now. Incredible anti-inflammatory benefits, also omega-3s, chia seeds,” she said.

Brown said those supplements improve memory and mood. Just a pinch a day of the spice tumeric does wonders for body and mind.

“One-eighth of a teaspoon a day is a great place to start, eggs to smoothies, salad dressing, tea,” Brown said.

Dr. Yadegar encourages us to maintain normal weight and body mass index, or BMI. He said belly fat is a precursor to other diseases.

“If you’re obese it increases your risk of heart attack, stroke, so you may not live long enough to benefit from that decreased risk,” Dr. Yadegar said.

He hopes the research that studies too fat versus too thin can be put to good use in developing new treatments.

Doctors say everything in moderation, but when it comes to fruits and veggies don’t skimp when putting them in your lunch.

Researchers said the next step is to examine if those who are overweight ingest dementia fighting nutrients in extra food that they eat.