This goes back to a previous post about guessing your nutrition...

Heres a fact, there are 4 calories in 1 gram of protein, 4 calories in 1 gram of carbs and 9 calories in 1 gram of fat. So, with this being said, if you are training to lose weight and your diet consists of eggs, fish such as salmon etc. nuts, whole milk, steak, and coconut oil for cooking in. 
All of these are high in fat (albeit good fat). You could very easily be eating a huge amount of calories without even noticing despite these foods being Healthy.

Just because a food is healthy doesn't mean it has invisible calories. Where some people go wrong is they forget the minor details, for example you may have 7 cups of coffee/tea a day with whole milk and 3 sugars and not even realise... these calories all add up!

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 Look at areas that don't look obvious to you if you're struggling to loose weight and you're doing everything else right.