Strawberries and Blackberries - are low in calories. Everyone needs calories, but eating too many foods which are very high in calories, like chocolate bars and crisps, is not a good idea. These foods contain a lot of fat and sugar which are just not very good for our bodies. If you feel like a treat, have some fresh fruit instead. A 100g/4oz bowl of strawberries has around 30 calories and makes the perfect healthy snack anytime.