1. Cereal

The gripe: "For the most part, cereals are not exactly high in nutrients, apart from synthetic nutrients that are added. Cereals are also low in protein and high in carbohydrates, so if weight loss is your goal, then it's going to be pretty hard if you're fuelling your body with carbs." Many cereals have a high glycaemic index (GI), meaning they're unlikely to keep you full and are likely to bring an energy crash. "In my experience, people who eat cereal for breakfast are generally the people who have the energy slump in the afternoon," Ellis says.