Short Answer: No! If you are eating the right fats and not eating it in excessive amounts.
I bet a lot of you are saying “Wait, what? I don’t believe you.” I know I have said these words quite a few times when anyone tells me this. The fact that eating more good fats may actually be good for you and not make you gain weight is something that has taken me a long time to even start to come to terms with and actually believe. It just seems like common sense that the more fat that you eat, the more fat you gain. Well, shockingly that isn’t necessarily true!!
How many times have you heard that eating carbohydrates gives you energy? As a former college athlete and runner I have heard this a lot. And it is true. When you digest carbs (sugars, starches, and fiber) your body breaks down these carbs into sugar which the body stores and uses for energy. 
This is all good and dandy, but if you’re burning sugar as energy you are not burning fat. Most of us, if we are trying to lose weight or become leaner, we want to burn off that excess fat! It turns out that if you cut some of the carbs in your diet and eat more healthy fats instead you can actually turn your body from sugar-burning into fat-burning!
When you eat carbs, your body releases insulin into your body in proportion to how many carbs you eat. Insulin is a molecule that controls how your body uses the nutrients that are put into it. Lower insulin levels that result from eating less carbs allow your body to more easily burn fat as energy instead of sugar. 
Also, if you aren’t eating any fat, your body won’t know/be good at burning it! The more fat you eat (again GOOD fats) the more efficient your body is at burning fat. Lastly fats keep you fuller for longer so you end up more satisfied and eating less.
- unsaturated fat
- polyunstaurated fats
- omega-3 fatty acids
- Ex: olive oil, coconut oil, salmon, tuna, avocados, nuts
- trans fats
- saturated fats
- EX: shortening, butter, beef fat, pork fat, vegetable oil
Now as with most things, this must be kept in moderation!! You can’t have a diet that is entirely fat because fat is also very high in calories and you need to be getting all your other nutrients also. If you go binge eat nuts, you aren’t going to lose any weight since nuts are so high in calories. The first time I tried giving up processed carbs I did just that. I needed to munch on something and I ended up munching excessively on nuts. Rather than losing weight I gained it and then abandoned the no-carb idea all together. The past few weeks I have been trying to eat little to no processed carbs again and am having much more success. I am making sure I don’t over-do it on the fats and am noticing I am leaner and even losing a couple pounds! Usually I have at least one snack during the day and one after dinner that is high in fat (nuts, raw granola bar, almond butter, etc) but always try to keep serving sizes in mind and stick to those pretty well. I am not always successful but definitely more successful than I was last time around!