The real problem is that people like to eat, and they prefer to eat foods that are high in calories. Also, once they leave childhood they prefer to minimize exercise. This is a bad combination, but it isn't unique to humans. What's unique to humans is that they can usually find a lot of reasonably tasty food with minimal effort.
Go watch lions in a zoo, and see how much they sleep. This is normal. If you want an animal to be active, you limit its food supply, and arrange things so that activity is require to get anything that isn't dead boring to eat.
N.B.: This effect is less marked in smaller animals because:
1) It takes less effort to move, and
2) Smaller animals need to eat more often.
But humans count as larger animals.
This is oversimplified, of course, but there is no magic dietary food that you can eat or avoid to solve the problem. He's right that we have no real need for sugar, but we also only need a small amount of fat. But if we eliminate both we tend to OD on protein, which has its own problems.
I think the best fad diet of recent times was the oat bran diet. It still didn't solve the problem, of course, but it was minimally harmful.
FWIW, I tend to avoid sugar, and minimize fats (with some exceptions for olive oil...but even that only in moderation). But I like to eat, and I'm not active enough....and I weigh about twice what I should.
The only group of people I'm aware of that aren't *vigorous* exercisers and aren't overweight are strict vegetarians...or orientals who eat a traditional diet, which is nearly the same thing. (Or very young...though even there the percentage of overweight is increasing rapidly. Probably because their ability to run around has been sharply curtailed over the last several decades.)