When it comes to weight loss or fat loss, the most simple and effective way to ensure success is to moderate your caloric spread and maintain a consistent deficit. With that said, that answer is not really why we're here - we want to know if consuming more fat will make you fat.
This is one of the main concerns that may keep you away from eating fat. When we look at the actual caloric energy received from carbs and protein (both 4 kcal per gram) we see that fat has more than double the calories (9 kcal per gram) per serving.
On the other hand, calories are not necessarily a clear indicator of weight gain - it's just more complex than that. Just because fat has more calories does not mean that by eating it you will put on weight.
Fat is also very healthy for you - when you consume the right type.
Polyunsaturated fats, monounsaturated fats, omega fatty acids, unsaturated fats - these are all really good sources of fat that you can find in many fat-rich foods like nuts, fish, seeds and beans.
Yes, a diet that is high in fat can work, but it is really dependent on the actual person. There’s a rule called the “equator rule” which roughly states that the closer your blood relatives, historically, were to the equator the higher your nutrient demand for carbohydrates would be.
Those from Caribbean countries, Mediterranean backgrounds, and anything close to the equator will have a very good ability to metabolize (in general) carbohydrates. If this population of people were to go on a high-fat diet, they may not experience the same benefits that other blood relatives, like those of Scandinavian heritage, would.
Whenever you look at what food you should be eating, it’s always good to make an objective assessment of where you came from.
Good food is good food, and this won't really change, but eating a diet that is as close as possible to what your blood relatives would have eaten is going to allow your body to function at the most effective rate possible.
The consensus, then, is yes and no. The research will show that pretty much any nutrient consumed in excess can lead to weight gain. The reality is we just don't have enough human trials to definitively say that it will.
Your best bet is to always strive for moderation.
In most cases, the most effective macro-nutrient split is 50% carbs, 30% protein, and 20% fat. Try sticking to those ratios for a while and then adjust as needed for your own body. You’ll be able to tell if eating a higher percentage of fat works for you or if it makes you gain unwanted pounds.