Fat is a double-edged sword when it comes to weight loss. On one hand, studies show fat helps you stay full between meals, and we all know it makes meals taste better. On the other hand, studies also show it is easy to over-consume it during a meal because it doesn't contribute to a sense immediate fullness like other nutrients.

A good compromise is to reduce fat intake to a moderate level.

A fat intake of 20 - 25% of total calories is a good guideline. Up to 35% fat is considered a "moderate fat" diet.

Here is a good strategy for keeping fats in check:

1) Monitor your fat intake, or it will add up very quickly. You can easily blow your whole calorie goal on a surprisingly small amount of fat. If you measure nothing else, measure any pure oils or fats you are using, such as for dressings, toppings, and spreads, and be aware of the caloric content. When it comes to taste, a little fat goes a long way - use that to your advantage. Recommended: Counting and Measuring

2) Eat a lot of fruits and veggies. That will automatically lower the overall calorie density of a diet that might otherwise be considered "high fat". That's the case with the Mediterranean Diet which can contain up to 40% fat, but because people also consume a large amount of vegetables, it reduces the overall calorie density. The result is a moderate to low CD diet.

3) Try to avoid combining fat with refined carbohydrates (sugar, white flour, etc). This can create "food with no brakes".

Here are some additional ideas for reducing fat without trying to eliminate it altogether.

Tips:

Use fat in high-enjoyment areas; reduce it in areas you don't care as much about. Do you care about butter on your toast more? Or more creamy coffee? Chocolate after dinner?
Switch to low-fat versions - they often taste just the same or only slightly different. Such as cottage cheese, mozzarella cheese, yogurt, fat-free half-and-half, salad dressing, mayo and more. (If they do happen to not taste quite as good you can quickly get used to them: it becomes your new normal such as switching from whole milk to 2%, then 1%, then fat-free)
You can keep the creaminess of soups and baked goods by substituting fat with plain yogurt or Greek yogurt, fat-free sour cream, pureed potatoes or other pureed veggies.
Eliminate the obvious: french fries, fried chicken, etc.

Other ideas:

Switch to a non-stick pan vs using cooking oil or spray
Salad can taste just as good without drenching it in dressing (the extra fat isn't missed)
Keep dressing on the side and dip salad into it with your fork
Grill to let fat drip off

Boost flavor in other ways instead of fat:

Cook in broth or wine
Add high-flavor veggies like onion and garlic to soups and other dishes
Add low-fat/high-flavor condiments like mustard, salsa, ketchup, soy sauce, hot sauce

Background Information

Fat used to be the enemy of weight loss (for logical reasons). And saturated fat used to be the enemy of health. But it's not quite that simple. Here are the details...

Low Fat Diet Reasoning

Fat contains twice as many calories per gram as both carbs and protein. Specifically, fat has 9 calories per gram compared to 4 calories per gram for both carbs and protein.

One tablespoon of 100% oil has 120 calories compared to one tablespoon of 100% pure sugar which only has 48 calories. Our bodies store any excess dietary fat (not required for immediate energy) as as body fat. See Losing and Gaining. (Note that the fat we eat in food is structurally the same as body fat and has the same 9 calories per gram).

Fat storage can be sneaky. Consider that 1 pound of body fat holds 3500 calories. You'd have to overeat fat by 3500 calories in one day, or 500 calories for 7 days to gain just one pound. It can be done, but it often happens gradually. Contrast that to carbohydrates which are stored in the body as glycogen, along with a lot of water weight. You only need to eat 600 calories of extra carbs to gain 1 pound of water weight, which you will likely notice the very next day! Carbs are, incidentally, a common reason for weight fluctuations -- and can hide what's really happening with fat storage. See Weight Loss vs Fat Loss.

Studies clearly show that during a meal, fat does not contribute to a sensation of fullness as quickly as protein and fiber does. Even carbohydrates are more satiating. That means we can eat a lot of fat during a meal without realizing it -- called "passive overconsumption" -- especially if we are unaware of the fat content (hidden fat) versus when we can sense it (like sensation of creaminess).

That's the main reasoning behind low-fat diets.

However, the reality is that very low-fat diets have a pretty poor track record for several reasons: people on low fat diets tend to consume high-density refined carbs as a substitute limiting fat often means people don't get enough protein (a filling food) super-low fat diets tend to be boring and bland fat helps you stay fuller longer

So, a boring diet that makes you hungrier sooner? That's a recipe for disaster.

But studies show that fat does help you stay fuller for longer between meals... it "sticks to your ribs". So -- some fat is actually a good thing for calorie control purposes.

Best Approach

There are two factors here:

Fat is the highest-calorie nutrient and it's easy to eat a lot of it at meal without realizing it. Cutting fat is an effective way to lower calorie intake.
Fat helps you stay fuller for longer and makes food taste less bland. Some fat is good for you. Cutting out all fat is a bad idea.

Thus, a compromise is best: Simple eat small, controlled amounts for taste, along with getting some healthy fats in your diet, like essential fatting acids (EFAs or fish oil), olive oil, hummus, avocados, and natural peanut butter.

That typically works out great for most people.

In fact, research proves just that a "moderate fat" diet is the easiest to stick with over the long haul.

High Fat Diets?

This works for some people. The main reason is because you typically have to eat high protein in order to to eat high fat, and high protein is a great diet food (for many reasons: see Protein).

If you eat high-fat you should also eat low-carb. A high-fat, high-carb diet is a certain recipe for gaining fat!

A high fat diet is something you have to try for yourself to see how it works.

Fats and Your Health

As far as health goes, you should get some essential fatty acids (EFAs or fish oil) in your diet. Eat fatty fish like salmon or take a supplement.

The latest news based on the research is that saturated fat (as found in butter, steak, etc) isn't unhealthy after all. It turns out you don't need to outright eliminate it from your diet. However, the debate may not be done quite yet and you'll still need to see what your doctor says.

This means the only fat everyone agrees is bad ... is trans-fat.

See Basic Nutrition for more.