What do you think is the leading cause of the obesity crisis?
Portion sizes have ballooned in the past 30 or 40 years. They've crept up slowly, and people aren't aware of this big portion problem. People eat more when they're presented with more food. They don't feel any fuller. It's almost as if it never happened. When people follow diets that are low in carbs or low in fat, it's usually high in something else. In my opinion, the problem is portions.

What is the big mistake that's leading to those expanding waistlines?
People worry too much about what they eat and pay no attention to how much they eat. They can rattle off any detail about a sandwich, but when you ask them how big that sandwich is, they're clueless. I think that's what gets people in trouble.

Why is portion size so important?
At the end of the day, if you want to lose weight, it's about calories. It's not about carbs or fat or protein. It's about eating fewer calories and expending more energy. Big portions have more calories, and when you're presented with more food, you eat more food. You have excess calories, and you don't know why you're gaining weight when you're eating the same things you always have. But the portions have doubled in size.