The trick here is not only to avoid all obvious sources of carbohydrate (sweets, bread, spaghetti, rice, potatoes), but also to be careful with your protein intake. If you eat large amounts of meat, eggs and the like, the excess protein will be converted into glucose in your body. Large amounts of protein can also raise your insulin levels somewhat. This compromises optimal ketosis.
If you eat a carbohydrate-rich meal (lots of pasta, rice, bread, or French fries, for example), your body releases insulin to help with the influx of all this glucose into your blood. As well as regulating blood sugar levels, insulin does two things: It prevents your fat cells from releasing fat for the body to burn as fuel (because its priority is to burn off the glucose) and it creates more fat cells for storing everything that your body can’t burn off. The result is that you gain weight and your body now requires more fuel to burn, so you eat more. Since insulin only burns carbohydrates, you crave carbs and so begins a vicious cycle of consuming carbs and gaining weight. To lose weight, the reasoning goes, you need to break this cycle by reducing carbs.
A sedentary lifestyle is one of the major causes of occurrence of belly fat. If you don’t indulge in any physical activity, and spend most of the time sitting, watching T.V., reading, etc., it is known as a sedentary lifestyle. Lack of regular exercise, or not exercising at all can lead to fat storage around the belly area. In other words, being a couch potato will make you fat.
Here's something else most people probably don't know: Fidgeting is good for you. It's considered a nonexercise physical activity, and it's an important way to burn energy. You get more health benefits if, in addition to exercising, you are a more fidgety, more active person the rest of the day. This means gesturing while you're talking, tapping your foot, just moving around.