Whether you're looking to lose or put on weight an essential tool is to get an idea of the calorie content of different foods. There are a few ways of doing this. One easy way is to look at food packaging and the recommended serving sizes. Other tools that our clients find useful are calorie tracking apps such as Nutracheck or MyFitnessPal.
On average, a woman needs 2,000 calories a day to maintain their weight and a man needs 2,500. This is just a guide, however, and does depend on activity levels and body composition.
So if you're looking to lose weight you'll obviously need to eat less calories and more to gain weight.
While sticking to good nutrition is important you don't have to cut out all the foods you enjoy - just be mindful.
To give you an idea, we've listed a few favourite sweet snacks so you can see how many calories are in each.

Mars Bar (51g) = 228 calories

Twix (2 fingers) = 250 calories

3 chocolate digestive biscuits = 258 calories (86 calories each)

Freddo bar (18g) = 95 calories

3 Jaffa cakes = 138 calories (46 calories each)

Dairy Milk bar (45g) = 240 calories