How Much Fat Do You Need?
Fat is needed for the production of hormones, absorption of vitamins (A,D,E & K), creating cell membranes and a whole host of functions that makes you all sexy and shit. In other words you need some, hence the name - Essential Fatty Acids.
There are 3 types of fatty acid, as well as cholesterol:
As a quick biochemistry note - fats and carbohydrates are made of carbon, hydrogen and oxygen; proteins also contain nitrogen. The terms saturated or unsaturated refer to whether or not all of the carbon molecules have hydrogen attached to them.
Monounsaturated have one double carbon bond and Polyunsaturated have multiple carbon double bonds.
In reality, no food is completely a saturated or unsaturated fat. Foods with fat in them contain a combination of the fatty acids so when we discuss foods high in them, please remember that we mean they have a higher proportion of them.
Saturated fats are generally solid at room temperature and are found in foods such as fatty animal meat (human body fat stores are saturated fats for example), coconut & coconut oil, full fat dairy (cheese, butter, cream, whole milk), chocolate and palm oil.
A little side note - Saturated fats are great for cooking as they are stable at high heats
There have been health concerns with large amounts of saturated fat in the diet in the past, mainly to do with cholesterol. It was found that saturated fat increased cholesterol in the bloodstream and cholesterol caused scarring of arterial walls which contributes to heart disease. It was therefore hypothesised that saturated fat would lead to me heart problems.
The problem with this hypothesis and what has been borne out since is that saturated fat can raise both good and bad cholesterol:
Cholesterol isn't used for energy, it is a steroid precursor and is used in the formation of various hormones (estrogen & testosterone for example).
When we hear about good and bad cholesterol what we are really talking about is the transport molecules that carry cholesterol around the body. Whether they are considered good or bad is determined by the amount of protein in the molecule.
- LDL - Low Density Lipoproteins
- HDL - High Density Lipoproteins
LDL has been shown to scar up the arterial wall which causes plaque to stick to the scarring and lead to a narrowing of the arteries, thereby putting greater pressure on the heart to pump blood through a narrower tube.
HDL however has been shown to have a beneficial effect on heart health as it does not scar the arterial wall and actively collects LDL that has built up on the wall lining.
BACK TO SATURATED FAT
Unfortunately at the time, all cholesterol was measured together under "total" cholesterol. And so when it was seen that eating saturated fats led to an increase in cholesterol it was assumed that this would be problematic.
The current Cochrane review on the matter found a link (a 17% increase) between saturated fat intake and cardiovascular disease, but not death. Although it seems that this may be avoided by simply increasing the amount of unsaturated fat in the diet rather than avoiding saturated fats. In other words make sure you consume a variety of fat sources in the diet.
One bonus about saturated fats is that they tend not to oxidise when cooking due to their double bond structure; as a result polyunsaturated fats (multiple double bonds) are much more susceptible to heat damage.
As the name suggests these are the single carbon double bonded fatty acids. They may well be beneficial for health (at absolute worst they're pretty neutral) and are the primary fat in Olive Oil; one of the main fats found in the almost always healthy Mediterranean diet.
I say almost as I don't trust writing that without someone eating a frankly ungodly amount and proving me wrong!
And so we arrive at polyunsaturated fats. They are almost always liquid at room temperature and include fish, nuts (walnuts in particular), vegetable oils, flaxseed and flaxseed oil.
They contain the only two essential fatty acids:
- ALA - Alpha Linoleic Acid
- LA - Linoleic Acid
However actually becoming deficient in them would require you to consume a diet consisting of Haribo with the occasional side of Skittles.
Polyunsaturated fats also contain the Omega 3 & 6 groups which have been shown to be pretty darn healthy. In particular they have been consistently shown to be beneficial for heart health.
- One of the reasons Fish OIl is commonly recommended is because of it's high amount of EPA & DHA; two of the three omega 3 fatty acids that most western diets are deficient in.
- For general health, 250mg of combined EPA/DHA is recommended. The American Heart Association recommends 1g per day, while there may be some reduction in muscular soreness at 6g per day.
- You could achieve this level of intake through the diet if you were eating large amounts of quality fish sources but for ease of use taking a few fish oil capsules a day seems a sensible bet.
Fat Macronutrient Targets
There appears to be a lower limit of Fat intake that if dropped below may negatively affect health and hormone production. That level seems to be around 15-20% of total caloric intake. Of course, this is hard to say for certain as it's confounded by the loss of body weight and body fat during a diet, which may itself be a large reason for the reduction in hormones we see.
But we have to remove calories from somewhere. We probably don't want to take them from protein and ideally we want to keep carbs as high as possible to protect gym performance. This is all done, hopefully without dropping below the 20% of total calories from fat recommendation....
Yeah you may notice a problem with actually being able to balance all of those things at certain points - near the end of prep for example.
And so at some point we may push the lower ends of this for short periods of time but for the rest of the time we're going to say at least 15% and up to 30% of intake should come from Fat.
Take Home Point
Adequate Fat is required to maintain a healthy, fully functional body
Under most conditions that level is between 15-30% of total caloric intake
GEMMA HAS 1450 CALORIES
At 15% of calories
(218/9 = 24)
24g of fat
At 30% of calories
(435/9 = 48)
48g of fat
TOM HAS 2850 CALORIES
At 15% of calories
(428/9 = 47)
47g of fat
At 30% of calories
(855/9 = 95)
95g of fat
Where To Find Fat
Fats are found in some quantity in most foods, other than sweets and some plants. Animal and plant produce can vary from hardly any to a surprisingly high amount, for example chicken breast compared to duck breast or spinach compared to almonds.
And so, as always, it's too simple to look just at "good" or "bad" fats, we must look at how they fit into the diet as a whole.
It is very easy to over consume calories from fats, mainly because of their higher calorie density per gram; 9 versus 4 in carbohydrate and protein. If you refer back to the previous article you will recall that they also have a lower thermic effect; 0-3% versus 5-10% in carbohydrate and 20-30% in protein. So generally speaking the calories we consume from fats are more readily storable.
If you eat quite a lot of ready meals or buy a large amount of your food on the go it can be surprising how much fat you may be consuming without realising it.
Get a set of scales and measure out a serving of nuts. Take a guess at how many grams are in my hand here?
Or in the amount of butter you put on your sandwich?
Fats are great and they do many wonderful things but if there is one place I'd strongly encourage you to be able to know a serving size on, it would be fat.