“Fat makes you fat right? No wait, you gotta eat fat to lose fat”… let’s clear up the myths from the facts once and for all.
What’s all the hype around coconut oil, avocados and nuts for helping me look better?
Will saturated fat clog my arteries and kill me?!
Should I eat the yolk or only the whites?
Dietary fat is an essential nutrient found in the foods you eat. It is one of the three main macronutrients and serves many essential functions in the body.
Fat is the most calorie dense macronutrient at 9 calories per gram. Pay attention here, as these calories quickly add up causing unwanted weight gain if not monitored.
Trans fats have been unquestionably shown to have negative health consequences.  In Denmark, Austria and Switzerland, they're believed so unhealthy – a complete ban in in place.
They are most commonly used to increase shelf life in baked goods such as muffins and cakes. They serve no purpose in optimising the way you look or your health and longevity.
An American study noted: for every 2% increase in energy from trans fats, there was a 23% associated risk with cardiovascular disease.  Stay away from them.
Saturated fats are found mostly in animal products such as, fattier cuts of meat, dairy products, butter and cheese.In recent years it's become trendy to consume large amounts of these fats.
Turns out, they're not the absolute killer and cause of heart disease once feared. I would still exercise caution, as overdoing it has been associated with other poor health outcomes. 
Saturated fats play a crucial role in testosterone production – beneficial for a whole host of reasons. 
These fats need to be in your food plan, but perhaps not to the extent of adding whole sticks of butter to your morning coffee!
A long-term study of 12,000 people, found swapping saturated fat and trans fat for polyunsaturated fat such as olive oil reduced the risk of dying by 27%. 
Found in plant oils, but also in animal sources as well. Consumption of these fats do not harm health.
The omega-3 and omega-6 fatty acids found in polyunsaturated fats are essential to survival and health. Your body cannot make theses, so you need to get them from your food plan.
In the West we have a slightly skewed omega-3 to omega-6 ratio –heavy on the omega-6s and typically not enough omega-3s.
If I gave you a list of how beneficial the omega-3s are for your overall health, you would think I was joking. Everything from heart health, depression to improved brainpower. 
Even muscle mass is improved with the consumption of omega-3s. You know when your mum said you should probably get some oily fish in a few times per week? She was right.
These fats occur mostly in plant foods and have been consistently shown to have positive health outcomes.  Common sources include nuts, nut butters, olive oil, canola oil and avocados.
Out of all your fat sources, these should make up the majority. A food plan high in monounsaturated fats can lower LDL ("bad") cholesterol and reduce risk of heart attack and stroke. 
Above from Understanding Healthy Eating by Mike Israetel and Renaissance Periodisation
Without enough dietary fat you can't absorb certain vitamins, hormonal health suffers, food tastes bland and you can experience other negative health consequences.
Your body can produce most fats, with the exception of omega-3s and omega-6s. These must be consumed through food.As mentioned above, dietary fat (especially saturated and monounsaturated) is important for testosterone production. 
Eating fat in and of itself does NOT cause you to gain fat. Body fat gain always comes down to an overall excess in calories, not just the calories from fat.
This is clear to see from the fat-loss success of a Ketogenic-style food plan. Over 60% of the foods on this plan come from fat.
The reason this style of eating is successful is because overall calories eaten is less than required.
Saying this, fat contains 9 calories per gram. Unlike protein and carbohydrate at 4 calories per gram, calories from dietary fat can add up quickly.
Fat also has a low thermic effect (0-3%), meaning you don't have to work very hard to store it, compared with protein (20-30%) for example. 
However, in efforts to gain muscle by overeating, it's unwise to have the extra calories primarily coming from fats. They don't help gym performance and more importantly, are more easily stored as body fat compared with carbs. 
Cholesterol is a waxy fat like substance found in all cells of the body. LDL is often referred to as “bad” cholesterol as too much is unhealthy, whereas HDL is often referred to as the “good” cholesterol because it is protective.
Although you may have been told as a kid not too eat too many eggs as it can raise cholesterol, dietary cholesterol has minimal effect on blood cholesterol because your body does a very good job at auto-regulating this.
When dietary cholesterol intake goes up, your body makes less and when you consume less cholesterol through from food it makes more.About 25% of the population are considered “hyper-responders”, meaning dietary cholesterol does modestly increase LDL and HDL, but not the risk of heart disease. 
Cholesterol plays an important role in muscle building as well – it’s the building block of muscle building (anabolic) hormones.
Oh yea, and you're good to eat your egg yolks, that myth got put to bed a while back. In fact, they are an extremely healthy, so if you can “fit in” the fat grams from eggs, I’d highly recommend doing so. 
As we’ve discussed, saturated fat is not the absolute killer that it was made out to be in the 80’s.
There is no relationship between saturated fat intake and health complications or premature death.  Even those with pre-existing heart disease,
Even though this recent study was scrutinised for some of the methods used in the trial, the conclusion of there being:
“insufficient evidence from prospective epidemiologic studies to conclude that dietary saturated fat is associated with an increased risk of coronary heart disease, stroke, or cardiovascular disease.” 
backs up quite nicely other studies that find no correlation between saturated fat and heart disease. 
Saturated fat is important to maintain high cholesterol and anabolic hormone levels, both of which are important for muscle growth.
Saying this, I would recommend your saturated fats come from whole foods and do not dominate your overall fat intake.
Researchers in the field of muscle, strength and body composition generally agree that an absolute minimum of 20% of your diet should consist of dietary fat.
Most recommend a 20–30% range, with the majority coming from monounsaturated sources.
This ensures essential fatty acids are consumed and there is some left for the potential benefits to testosterone.
Food also taste better in this range. Improvements in metabolic and cardiovascular health may also be achieved.
An average male consuming 2,500 calories per day – 25% of this coming from fat would be 70 grams of fat per day.
My clients who don't do so well on higher carb food plans, I have no problem raising dietary fats to 35-40% of their plan. Some guys feel much better on a higher fat intake.
Food plans with 40% coming from fat compared with 20% always have better testosterone profiles. 
However, going too high in fat may compromise amounts of carbs and protein, which also needs to be taken into account. It’s something you need to experiment with yourself and is highly individual.
Saying this, there are very few times I would advise going below 20% ... and even then it would be for a short period of time.
The vast majority of this list are monounsaturated fats, with a few saturated fats in there as well.
If you aren’t eating 2–3 servings of fatty fish per week, I would strongly recommend supplementing with a decent omega-3 fish oil. This ensures you get 2–3 grams of omega-3 daily.
HIGH IN OMEGA-3s
• Dietary fat is an essential part of any balanced food plan.
• Fats come in four types:
• Trans fats
• Saturated fats
• Monounsaturated fats
• Polyunsaturated fats
• Trans fats should be avoided
• Omega-3 and omega-6 fats cannot be produced by your body – they must come from food.
• For optimal health, at least 20-30% of your food plan should come from healthy fats.
• A good dietary fat split to aim for is: 45% monounsaturated, 35% polyunsaturated and 20% saturated fat.
• Adequate fat intake is essential to optimise testosterone levels.
• Eating fat does NOT make you fat – overeating make you fat.
• There is no correlation between eating saturated fat and incidence of heart disease.
• Eating foods containing cholesterol and saturated fat does not increase cholesterol levels.
• Supplementing with a decent fish oil is a good way to optimise your omega-3 levels.
 Associations of egg and cholesterol intakes with carotid intima-media thickness and risk of incident coronary artery disease according to apolipoprotein E phenotype in men: the Kuopio Ischaemic Heart Disease Risk Factor Study