This is a fairly good little article - bbc.co.uk/news/magazine-268...
And it does help you realise (without getting into just TOO much detail / technobabble) that nutrition is quite a complex thing.
Which is why issues such as weight loss can't always be simply boiled down into one-liners or simple slogans.
Whatever approach you are taking to weight loss, and wether you're being successful with it or otherwise, remember it is important to ensure you are taking in the full range of nutrients. So do get in the fish and the green veg and the fruit - they really do make a difference.
Good luck with your weight loss journeys.