“And this dietin’, dietin’, dietin’, dietin’
Sure is a rough way to die…”
Bobby Bare, ‘Diet Song’
Losing weight is complicated, right? Well, maybe not as confounding as sorting through the endless supply of diet books and fad diets (most of which are basically the same nonsense repackaged and rebranded for the next up-and-coming celebrity fitness “expert” to sell). Truth be told—and the truth is hard to come by—the basic concepts of weight management are easy. It is filtering out the nonsense that people find most challenging.
So, what is it? High carbs? Low Carbs? High Fat? Low Fat? High-frequency meals? Intermittent fasting? Do calories really matter? etc. ….
I listened to an “expert” address two “myths” of dieting, and, like every “expert”, he had some things right and many more things wrong. Funny the guy’s podcasts are supposed to be simplifying nutrition when in reality it is the same over-complication of the same basic principles of human nutrition.
The first “myth” was that calories in = calories out. He was right in pointing out that this isn’t true per se. It isn’t a simple matter of counting how many calories I consume and how many calories I expend (i.e., basal metabolic rate + physical activity). There is a lot more going on—much of which we can’t easily get a handle on. There is the thermogenic effect of food (i.e., the energy cost of processing the foods we eat—roughly 10-15% of the calories we consume). We are learning that the actual usable calories from certain foods are not what we find on the food label. This varies by food—almonds, for example, apparently, only provide 70% of the actual calories stored in the nut (thus, when eating some foods we may not be eating as much as we think). This varies, as well, on the individual digestive system. Bacteria in the gut, for example, vary among individuals leading to variability in the amount of food energy that actually gets absorbed. (My students and I had a very unpleasant and enlightening discussion about “fecal transplants” recently. The Only Human podcast had an insightful discussion on the “calorie” that is worth the listen: https://itunes.apple.com/us/podcast/only-human/id1042116072?mt=2&i=362497112.) In addition, the method of cooking may also impact the calories that get absorbed. Basal metabolic rate (BMR) is measurable, but is not something that is easily obtained (precisely, at least). BMR can be estimated, however. I recommend most any online calorie counter. Caloric expenditure through physical activity can vary, also. At best, we are usually only estimating caloric intake and expenditure. So, in a general sense, “calories in” does not necessarily equal “calories out”, but this is splitting hairs. All things considered, if you consume more than you expend (on average), you will gain weight, and vice versa. A big question remains: What kind of weight do you want to gain/lose? Are you gaining/losing muscle or fat?
The second “myth” addressed was that carbohydrates are the preferred fuel source in humans. It is true that fat is not the evil that nutritionists and cardiologists have painted it to be in recent years, but…. What is false is that we can adapt our diet to make fat our primary fuel source…and still perform.
From a weight-loss perspective, true, one can lose a significant amount of body fat by eating a high-fat diet (75-80% fat). This is called a ketogenic diet. It works because fat can’t be metabolized effectively. You see, fats need carbohydrates to be fully metabolized—to obtain all of the available stored energy. It is beyond the scope of this blog, but, essentially, when glucose is not available, fat cannot effectively enter the oxidative energy systems (the Krebs or tricarboxylic acid cycle, to be specific) and gets converted to ketones, wasting much of the stored energy. (Think of it as putting premium gasoline in you ’73 Dodge Dart.) This is great for burning fat, but poor for performance.
Bodybuilders often use a ketogenic diet in the final stages of cutting. Notice, I wrote “final stages”. A bodybuilder would never consider a fat adapted (i.e., ketogenic diet) long-term. Why? Because muscle demands carbohydrate to perform! Fats only can fuel muscle at rather low intensities. Muscle needs glycogen (stored glucose). One can build muscle only through intense effort, and such effort needs carbohydrates.
So, while it is possible for someone to be “fat-adapted”, it is important to understand that they will only function well in a more sedentary state—and possibly with low intensity aerobic physical activity. If one is exercising regularly, they will need some carbohydrates. I mentioned these numbers previously, but, in case you haven’t been following this blog, here they are again:
- 0.5 g/lb for non-training days (and, by extension, I would say for sedentary individuals
- 1.0 g/lb on light training days (for people with sedentary jobs and who exercise more moderately)
- 1.5 g/lb on moderate training days
- ≥2.0 g/lb on heavy training days (Source: Dr. Mike Israetel, The Renaissance Diet).
Notice that carbohydrate intake is relative to activity level. So, true, when we are sedentary fewer carbs are necessary, and we can manage with more of our calories coming from fat. (But, be aware that on non-exercise days our calorie requirements are lower, so cutting carbs is, first, cutting caloric intake. Increased fats will help curb hunger, but should still fall within our daily requirement.)
Carbohydrates (especially sugars) can be bad in excess. A diet too high in sugars is certainly unhealthy (everyone: say “diabetes” with me….). One should be careful with what carbohydrates they do eat.
Fats are also a necessary component of our diet. We need fats to function. In fact, cholesterol—in moderation—is an essential component of the diet. Important hormones, e.g., testosterone, are made of cholesterol. We can’t (nor should we) avoid fats entirely.
Rather than try to be “fat adapted”, I suggest, we:
1) limit our caloric intact to promote a modest fat loss (and add muscle according to one’s taste and commitment to exercise);
2) eat a moderate amount of fat (30-50% of the total calories seems near ideal);
3) cut out sugary foods as near to completely as is reasonable (I mean, come on, we all love desserts at least occasionally);
4) eat complex (i.e., slow digesting) carbohydrates to avoid insulin spikes that are associated with gains in body fat; and, of course,
5) exercise regularly.