To be fair there are a lot of calories in carbs and so called "healthy" foods, but from my point of view, if they're good calories (eg not the crap you get in fast foods) then you're usually ok.
Obviously a healthy exercise plan is needed as well.
Healthy != low calorie, this is something people need to remember. A banana can be circa >100 cals (not 50 as above, rofl, poverty bananas), so a few of them will bump up calories. Nuts are a healthy food, but very calorific. Red meats are very fatty as well as protein-based, so are high calorie. Now I know you are aware of this, but people need to realise that healthy is NOT the same as low calorie. It's just getting them from a good clean source.
Junk such as low fat yugurts should be disappearing from people's diets. Rammed full of sugar and dairy based which is not easy for the body to break down. It's junk like this that will encourage your body to retain water and make you look puffy and bloated.