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Comparing the Diets: Part 3

Having examined the traditional high-carbohydrate/low-fat in Comparing the Diets: Part 2, I now want to look at the second major diet ‘type’; moderate-carb/moderate-fat.

A quick note on the percentage nutrient notation: as much as possible I tried to adhere to a format where the percentages represent percentages from protein/carbohydrates/fat in that order. So a notation of 30/60/10 means a diet where 30% of the calories are protein, 60% are carbs and 10% are fat.


The next major dietary camp refers to any diet consisting of relatively moderate carbohydrate and dietary fat intakes. This includes diets such as Barry Sear’s “The Zone”, Dan Duchaine’s “Isocaloric diet”, 30/40/30 nutrition and others. Such diets generally recommend a macronutrient split based on fairly equal amounts of protein, carbs and fat. Various scientific rationales, usually involving hormonal control are typically given.

The Zone, for example, recommends a 30/40/30 split while Dan’s Isocaloric diet is 33/33/33. Some bodyuilding gurus recommend 40% protein with 30% carbs and fats, for what it’s worth. In the research realm, cutting edge diabetic diets are in the realm of 15% protein (too low for athletes but protein can stimulate insulin release in diabetics), 40-45% carbs and up to 40% fat from mono-unsaturated sources. All of those approaches to fall within the description of moderate carbohydrate and moderate fat I gave last chapter.

Although I find a lot of the scientific rationales given for such diets to be pseudoscience at best, I do think that this type of moderate approach is probably close to ideal for most individuals. As I mentioned above, my ideal high-carb/low-fat diet is already close to 25-30% protein, 45-55% carbohydrate and 20-30% fat or so and moving from that to an Isocaloric or Zone diet is a rather minimal change to begin with.

But rather than focus on issues of eicosanoid balance or what have you, I simply think of such diets in terms of the fact that they tend to control blood glucose and hunger better because of the lowered carbs and higher fat content. It’s a fairly simple trick, the increased dietary fat (and usually fiber) slows gastric emptying; the decreased carb intake decreases the overall glycemic load.

Such diets also allow more food freedom and taste better than their near zero fat counterparts; this adds up to increased adherence. Frankly, if the various diet book authors had simply said “Hey, here’s a diet that better controls blood glucose and insulin and blunts hunger by slowing gastric emptying and it doesn’t taste like cardboard so you’ll stick with it better.” instead of making up physiology, I don’t think there’d be as much criticism of such diets.

So what people might find such an approach to be ideal? As I described above, for that small percentage of individuals who are genetically very insulin sensitive, or who are burning a tremendous number of calories (from carbs) with daily or near daily workouts, the high-carb/low-fat diet described in Comparing the Diets: Part 2 intakes are probably more appropriate. At the very least, they can be tolerated. Since that describes a rather small percentage of people in the first place, I find the moderate- carb/moderate-fat approach more appropriate under most conditions.

For people burning less calories (or carbs) during the day, there’s simply no real need for the high carbohydrate intakes of the high-carb/low-fat diet. Folks doing more realistic levels of activity (perhaps an hour of weight training 3-4X/week and moderate cardio), carb requirements simply aren’t that high. Again, read How Many Carbohydrates Do You Need? for more details.

From a caloric control issue, by lowering carbohydrates, and raising dietary fat, digestion is slowed and blood glucose levels tend to even out (note: the major effect is from reducing carbohydrates, fat is simply a caloric ballast). This generally means more stable energy levels and less pronounced hunger. This also allows foods higher on the GI to be chosen if desired with less of a problem.

Basically, while it’s generally better to choose lower GI foods from a health standpoint but GI becomes far less crtical when total carbohydrate intake is decreased. Remember that the glycmic load is the GI times the grams of digestible carbs: reduce digestible carb intake and GI becomes less important. Breads, pasta, rice and the rest can be consumed in controlled amounts on such a diet with far fewer problems. I’d note again that these foods may not provide much actual food volume when calories are restricted.

Another potential benefit is that, by reducing carbohydrate intake, muscle glycogen is generally maintained at slightly lower level. As I’ve discussed in books such as the Ultimate Diet 2.0, lowering muscle glycogen enhances whole-body fat burning. At the same time, the moderate carb intakes should be sufficient to sustain performance in all but the most extensive types of training.

Moderate-carb/moderate-fat diets also tend to limit problems with insulin resistance related blood sugar crashes as a consequence of both reduced carbohydrate intake and increased dietary fat. However, some extremely insulin resistant individuals still run into problems with even moderate carbohydrate intakes. For such people, a more drastic decrease in carbohydrates may be necessary.

As well, those individuals who find that eating carbohydrates makes them want to eat more carbohydrate can also run into problems even with moderate carbohydrate intake. As I discuss in The Stubborn Fat Solution, lowering carbs tends to enhance stubborn body fat mobilization; however larger reductions than those which occur in the moderate-carb/moderate fat diet may be necessary for extremely lean dieters.

I should mention, that moderate carb/moderate fat diets tend to be more of a planning hassle than the other diets, especially at first. While I don’t believe that you have to be exact in the percentages (as long as you get in the ballpark, you’ll be fine), it can still be a pain in the butt to figure out meal plans.

From a simplicity standpoint, it’s pretty easy to reduce fat and it’s pretty easy to reduce carbs; getting moderate amounts of each can be a hassle. As well, with practice and time, it becomes relatively trivial to eyeball meals to get in the right ratio.

And that’s that for the moderate-fat/moderate-carb approach.

I’ll discuss low-carbohydrate/high-fat diets in Comparing the Diets: Part 4.

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