1- Nuts:
It's true that nuts contain a lot of omega oils, the good fatty acids needed for a healthy brain functioning. But nuts are also high in calories, so they can easily add a few inches to your belly if you don't watch your quatity.. 1 small handful a day is enough for your health.
2- Avocados:
Avocados are loaded with good fat indeed, but unfortunately, one avocado has about 250 calories, and some people drink it too! So just add it to you salads, one a day is enough! Many trainers recommend consuming it too as they are rich in omega-3 which improves performence..But they are packed with calories and will lead to weight gain if you aren’t exercising enough.
3-Olive oil: 
Yes! Virgin olive oil can protect you from a heart attack.It does increase your HDL levels and decrease your LDL levels.. But one teaspoon of olive oil has 45 calories, so just be careful about your quantity!
Note that olive oil can only be used for raw food like salaas, so don't try to fry an egg with it, it will undergo the hydrogenation process, and become a Trans Fat, means pure cholesterol..
4- Smoothies:
A lot of you start their day by just mixing 3 to 4 fruits together with some milk.. Smoothies are tempting healthy food, tasty as well! But don't forget that smoothies are high in fructose ( fruit sugar), and extra fructose will increase lipid levels in your body.
5- Granolas:
They are extremely healthy and tatsy! But those munchies are high calorie food and consuming them at a wrong time can lead to weight gain. You can have a bowl of Granola in the moring with a glass low fat milk.. Do not snack on that throughout the day..
6- Protein bars:
That's the new trend! Protein bars are advertised as a healthy option for people who work out. It's true that they help repair muscles after exercise, and they really contain high amount of proteins per bar. But manufacturers load them with sugars in order to make them more pleasant and tasty. Protein shakes are a better option.