Maintaining a flat stomach is challenging. The key is being lean, not doing endless situps. Your stomach will stay flat as long as you maintain a caloric deficit by not eating more than you expend, but as soon as you start eating more calories than your burn, your body will start turning the excess into fat. Certain foods will cause you to gain fat more quickly than others because they are high in calories but low in nutrients. Never eating these foods will help in your goal to have a flat stomach.
Fatty meats such as many cuts of lamb, beef and pork are high in saturated fats, the bad kind of dietary fat you should avoid. They lead to high cholesterol, clogged arteries and heart disease. Saturated fats are also high in calories, so eating too much of them can lead to weight gain. Choose lean chicken or fish instead of fatty meats, or eat no meat at all. SUGAR
Sugar is nothing more than empty calories, and you do not need it in your diet. Whenever you eat a sugary food or beverage, like candy or soda, the calories are quickly stored as fat if they are not burned up immediately. Stay clear of anything that has sugar added to it, such as candy, cookies, cakes, ice cream and soda.
White foods such as white pasta, white bread, biscuits or any other baked good or food made from white flour, have almost no nutritional value because they are heavily processed and are mostly empty calories. Many white foods also have sugar and trans fats added. They fill you up temporarily but leave you craving calories from real food that your body can use. What's worse: Instead of eating something nutritious, many people just eat more white foods to fill them up again.
Alcohol is high in empty calories, just like sugar. To make things worse, many alcoholic beverages are mixed with other sugary liquids, like soda or simple syrup, which add more empty calories. In addition to being full of empty calories your body will store as fat, alcohol is also catabolic, so it will actually break down your muscle tissue. Now you're getting the worst of both worlds: gaining fat while you're losing muscle.
Potato chips are loaded with useless calories. One serving of Lay's potato chips, which is about 15 chips, is 160 calories. The big problem is chips are not filling, and people generally eat more than one serving in a sitting. You can get 160 calories from eating a couple handfuls of potato chips that won't fill you up, or you can get 160 calories from eating a handful of nuts or a large piece of fruit that will.