Balanced with 2 of the 3 major nutrients (fat, protein, carbohydrates) with at least a couple grams of fibre.-a snack thats going to keep your energy up for hours needs to have a balance of carbohydrates, protein,and fat-or at least two of the three. in fact, carbohydrates are your bodys main source of energy (and your brains preferred source). combining carbohydrates with fat and protein will give you a balanced snack which will help sustain your energy levels. a snack containing around 150-200 calories is an appropriate snack for people sticking to a diet below 2,000 calories a day. if your calorie needs are above 2,000 per day, aim for snacks that are about 200-250 calories each. fibre keeps you feeling satisfied for longer, so make sure your snacks pack in at least 4 grams of fibre. fat also creates a feeling of satisfaction, so dont be too enticed by fat-free snacks. avoid going too low in calories and/or fat-its likely your snack will leave you hungry for more in no time.