Processed foods are tempting and tasty, but many of their nutrients have been removed.

For instance, when carbohydrates are processed, their fiber is removed. This increases their rating on the glycemic index, a measure of how fast a food causes blood sugar to rise after eating. Foods with a high glycemic index tend to spike blood sugar levels, which then quickly decline.

That spike is why people might temporarily feel full after eating a bag of potato chips, but become hungry again soon after, when their blood sugar levels drop rapidly.

Foods that have a lower glycemic index, such as almonds, are digested more slowly and do not cause sharp rises and drops in blood sugar. Therefore, those foods are more satisfying for a longer period.

Sugared cereals, cookies, crackers, instant meals, and most other processed foods have high glycemic indices.

Previous studies suggest that a high glycemic index diet may increase a person’s risk for Type 2 diabetes, and developing diabetes doubles the risk for dementia.

The next time you’re tempted to eat a second helping of apple pie, consider having a handful of berries instead. The latter can be just as sweet while fighting the brain-damaging effects of oxidation.