How Much Fat?

A reader asks:

I've been keeping a journal tracking every single thing I eat. I was just wondering if you thought there was a limit that should be put on fats. For example, today was 119.1, it was from eggs, bacon, cheese, EVOO and pepperoni, it seemed way high and I was just looking for some input if you have time.
Thanks

This is a great question, and one that concerns many people. The simple answer is no, I don't think there's a limit on fats, at least not the way most people think of it. We've been taught for a long time that fat is dangerous, that it will give us heart disease and cancer, yadda yadda. We've also heard over and over that a low carb diet is a "high protein diet."

I want you to discard both of those notions. Properly constructed, a low carb diet is a moderate protein, high fat diet. A low carb, low fat, high protein diet is not healthful, and can, indeed, make you ill, as old-time woodsmen and pioneers learned when all they could get was rabbit and other very lean game. You should be getting the bulk of your fuel calories from fats. I aim for 65-75% of my daily calories from fat.

How much protein should you be getting? Shoot for a minimum of a half a gram for every pound of body weight -- in other words, divide your weight in pounds in half, and that's the minimum number of grams of protein you should get. (For those of you in the civilized world, you can just go for a gram per kilo. Near enough for government work.) You do want to get at least that minimum, because your body will be using protein to create what little glucose your body actually needs, and if you don't get it in your food, it will break down muscle tissue to make up the difference. My very conservative nutrition textbook says you can eat up to twice that, no worries.

Should there be any limit to fat? Well, maybe, but not because it's fat and therefore eeeeevul. Some of us find that we do need to limit calories modestly, even on a low carb diet. Yes, there really is a metabolic edge that lets you eat more calories than you could on a low fat/high carb diet and still lose weight, but it appears to be good for an extra 200-400 calories per day, not 10,000. I, by way of example, do best on somewhere below 2200 calories per day, and when I keep track I seem to veer from about 1600 to about 2200 and back, naturally.

Let's look at this a little more closely. Let's say that you weigh, to pick a nice round number, 150 pounds. That means your minimum protein requirement is 75 grams per day. Protein has 4 calories per gram, so you'll be getting 300 calories from protein. (Yes, your protein foods will probably contain fat, too, as well they should. But we're ignoring that right now.) And let's say you're sticking to no more than 30 grams of carbohydrate per day. Carbohydrate also has 4 calories per gram, so that's another 120 calories, for a whopping 420 calories, total. So if you've found you lose well on, to choose another nice round number, about 2000 calorie per day, you've still got 1580 calories to go, and those calories are going to come from fat. Since fat has 9 calories per gram, you're going to be eating... are you ready? 175 grams of fat per day. That works out to 88% of your calories from fat.

However, you might very well go for more than the minimum protein; many of us do. Let's say you eat 125 grams of protein, or 500 calories worth. So you've got 500 calories of protein, and your 120 calories of carb (because that's going to remain relatively inelastic). You're going to get 1380 calories from fat, or 153 grams of fat. You're down to 77% of your calories from fat.

But wait! You've discovered that you really need to stay around 1800 calories per day, a not-ungenerous amount. Sticking with 500 calories worth of protein and 120 calories of carbohydrate, you're down to 1180 calories worth of fat, or 131 grams. Down to 72% of your calories from fat -- still a high fat diet, for sure, but lower than 88%.

You see what's happening here? The fat fraction of our diet is the most elastic fraction. We really shouldn't eat less than our minimum protein requirement, and most of us don't want to go down any further on our carbs, which we've slashed to the bone as it is. So if we're going to adjust anything, it's going to be fat.

(I should add here that the fourth class of calorie-containing substance is alcohol, with 7 calories per gram. The days when my fat falls at 60% or less of my calories are generally days when I've had a couple of glasses of wine.)

All of this being said, many,and perhaps most, people find that so long as they keep their carbs very low, they can trust their appetites, and the calories take care of themselves. I've found that my best approach to knocking off a few pounds when I get into the "Red Zone" is to go to just meat and eggs -- no dairy, no nuts and seeds, not even vegetables (but, I confess, often an ounce or so of my homemade Splenda-sweetened chocolate) and no alcohol. I deliberately go heavy on the fat, however, on meat and eggs days, eating fatty meats like pork shoulder or spare ribs or rib eye steak, frying my eggs, and having sausage or bacon with breakfast. Because of the natural appetite-suppressing qualities of such a diet, I rarely get above about 1800 calories eating this way, but fat as a percentage of my calories goes even higher than usual. I feel remarkably good eating this way; my energy is high and my mood ebullient.

Do, of course, eat good fats. What are good fats? Not what you've been led to believe. I favor meat fats, especially if I can afford grass-fed meat, and butter, plus the fats in eggs, nuts and seeds, and avocados. I do use some olive oil, but am just as likely to use bacon grease (which, you may be surprised to learn, has more monounsaturated fats than saturated ones) and coconut oil, and I have a container of unbleached, unrefined lard from pasture raised pigs in my refrigerator. I am actually most wary of vegetable oils, because of their high omega-6 content, and the fact that they oxidize readily. I do occasionally use commercially-made mayonnaise, which generally contains soy oil; on those days I take an extra fish oil capsule at night to balance it out.

The whole "let's replace traditional animal fats with vegetable oils" thing turned out to be a big, big mistake. When I was a kid there were ads on television, touting this or that vegetable oil as "the most polyunsaturated!" Those ads have passed quietly from our televisions. Why? Because it turned out that all those omega-6 polyunsaturates were causing inflammation, cancer, and, yes, heart disease. Eat the fats your ancestors ate.