Rock Doc

By DR. E. KIRSTEN PETERS

While I have been dinking around for months, trying to lose five pounds, two of my friends have gotten serious about weight loss. Each of them is down 50 pounds. I'm pleased for them, of course, and truly impressed by their accomplishments. Successfully combatting overweight and obesity is one of the best things people can do for their health. It can help everything from joint pain to heart function, from Type 2 diabetes to certain aspects of mental health.

But it's not always easy to know what we should eat. How many calories are in a slice of pizza or a baked potato?...