Fats are created when you consume more calories than you burn. Most of people simply aren't able to measure how much they eat and how much are they active daily. Many other things affect on the energy balance, like high level of cortisol (hormone which is related to stress) which slows down metabolic functions and increases creating fats. You can decrease the level of cortisol by less exposure to stressful situations and organizing your daily schedule. But these changes are almost insignificantly. It's on you only to pay attention on your calorie intake.
You probably know that fats in your organism are stored in fat cells. Most of those cells are directly under the skin, but small part is located in abdominal cavity and is called abdominal fat. Fats can even appear on undesirable places like liver or pancreas. Your look depends about those fats under your skin. Getting or losing fat depends about calorie balance. Fat surplus occurs when creating amounts of fat exceeds ability of fat oxidation. Fat deficit occurs when amounts of fat are smaller than ability of their oxidation.
When you eat fats, you won't stimulate them to better oxidation as is the case with proteins and carbohydrates. Fat intake doesn't have any impact on absorption of other nutrients.
Carbohydrates are converted to fats only when you overeat with them, when you consume huge amounts of carbohydrates daily. Amount of carbohydrates which will be converted to fat depends about your daily activity and size of your muscle mass. When your amounts of carbohydrates are filled and you consume too much calories daily, the rest of carbohydrates you consume will be converted in fat, what is more often in people with too much level of insulin who have more developed lipogenesis. Those people are predetermined to weight gain more than others. Lipogenesis is the process of fat production. The opposite effect is called lipolysis, what means degradation of fat.
When you eat too much carbohydrates than your body needs, your organism precipitates more fat. It's happening because surplus of carbohydrates stops fat oxidation (fat burning). While you are in carbohydrate surplus, all fats you eat are precipitated as fat cells.
It's the same story with proteins. When you eat too much proteins than your body needs, oxidation of carbohydrates and fats is decreased. This way is created bigger surplus of carbohydrates and fats. That means that too much proteins can indirectly make you fat. Consumed proteins are most burned because they release most of warmth. It is very hard to be in protein surplus so it's little probability that you get fat because of too much protein intake.
If you don't understand everything, I can explain you all this on the other way. Amount of fats that you consume isn't changed, but surplus of the carbohydrates or proteins causes decreased oxidation of fats. Carbohydrate surplus causes increased oxidation of carbohydrates and decreased oxidation of fats, therefore most fats that you consume are stored as fat cells. However, it's very little chance for you to get fat of too much proteins because it's very challenging to consume sufficient amounts of proteins per one kilogram of bodyweight if you are bodybuilder. It's much easier to overeat with carbohydrates because most of the food contains great amounts of carbohydrates. Junk food is very rich in sugars (fast absorbing carbohydrates). Many people who are overeating with that kind of food have problems with overweight.
Have you ever asked yourself why not to completely eliminate fats from your diet plan? If you think that non-consuming of fats will help you to lose weight, you are wrong. When you eat too much of carbohydrates or proteins or both, lipogenesis is guaranteed and you are getting fat. If you consume too little fats, then your body starts to convert carbohydrates, and in rare cases proteins, in fats. The main point is very simple: Don't eat too much because you will get fat. Pay attention on those things when organizing your diet plan.