Self-styled experts often attribute various side effects to long-term
high-protein diets—dehydration, calcium and bone loss, kidney disease
and even increased bodyfat. The latter is based on the fact that protein
contains calories, and taking in too many calories inevitably leads to
gaining bodyfat.
A gram of protein contains four calories, the same as a gram of
carbohydrate. Fat is the most concentrated source of calories at 9 1/2
per gram, but according to many nutrition pundits, that doesn’t matter.
It makes no difference if you focus on a particular
macronutrient—protein, fat or carb; if you consume more calories than
you burn as energy, the excess will be stored as bodyfat.
Low-carb-diet proponents vigorously object to what they consider to
be an oversimplification. It’s more than just a case of excess calories
causing excess bodyfat, they say. There is also a hormonal interaction,
namely insulin.
Insulin is indeed the most fattening hormone in the body.
Whenever it is secreted, fat is either being maintained or synthesized.
Among other functions, insulin blocks the activity of various enzymes
that are involved in fat mobilization from fat cells as well as the
actual oxidation, or burning, of fat.
Because of that, having a simple carbohydrate—a high-glycemic-index
carb—prior to training will block the use of fat as fuel due to the
higher insulin release that results. That effect lasts for an average of
four hours after the high-carb meal is eaten. The general
recommendation is that if you consume any carb prior to training, it
should be from a low-glycemic-index source, which will cause less of an
insulin release and promote more fat burning.
Even so, the low-carb devotees go further, claiming that calories are
less important than carb intake for losing bodyfat. As evidence, they
point to published studies that found more fat loss in people who ate
low-carb diets than those who ate more carbs, even when the diets
contained the identical number of calories.
Low-carb diets not only control the harmful effects of insulin but also produce a higher thermic effect after meals.
“Thermic,” or “thermogenic,” effect refers to the dissipation of
consumed calories into heat. It’s also known as futile energy cycles,
since no work is done to dissipate the calories.
Critics of low-carb regimens call this “metabolic magic”—meaning
nonsense. A calorie is a calorie is a calorie, they say, and when it
comes to ultimate fat loss, how many calories you take in compared to
how many you burn is the ultimate arbiter. As evidence, they produce
studies showing that while low-carb diets do tend to bring more rapid
and greater rates of fat loss initially, as time goes on, it evens out.
At the end of a year the fat-loss rate for low-carb diets and other
diets is about the same, assuming that they contained the same number of
total calories. The naysayers hold that insulin alone cannot make you
fat unless you take in an overabundance of calories.
Then there is the protein issue. One of the established tenets of
low-carbohydrate regimens is that you must increase your protein. It’s
based on a number of established roles of protein in the body. For one
thing, a higher protein intake is known to help maintain lean mass,
mainly muscle.
Critics of low-carb diets like to point out that the body requires a
certain amount of carbohydrate to function properly, an assertion that
is not based in science. In fact, there is no established carbohydrate
requirement. One reason is that other substances can be converted in the
body to the main carbohydrate it uses—glucose.
As such, lactate,
glycerol from fat and amino acids from protein can all be converted into
glucose in the liver. Consequently, carbs are not essential.
All that said, you don’t want to avoid carbs all the time. In some
cases they offer definite advantages, such as for those engaged in
endurance sports or training. A minimal amount of carb also plays a role
in anabolic recovery processes following training, a key reason that
you should never consider a zero-carb diet.
The low-carb diet features a higher protein intake because the excess
protein helps to spare muscle that might otherwise be degraded for
energy. The branched-chain amino acids are particularly effective in
that regard. Other reasons for taking in more protein as your calories
or carbs drop is to help control appetite, since protein helps you feel
full when you’re dieting.
Eating more protein also appears to maintain the resting metabolic rate, which ensures optimal fat loss.
What about the notion that taking in too much protein can make you
fat? The pragmatic experience of generations of bodybuilders disputes
it. While the suggested optimal intake of protein for bodybuilders is
1.7 grams per kilogram—2.2 pounds—of bodyweight, in actual practice most
bodybuilders get far more than that. Considering the ubiquitous
presence of protein in meat, chicken, turkey, eggs, milk and so on,
along with the generous intake of protein supplements and
meal-replacement powders, it’s not that difficult for many bodybuilders
to take in two to three times more than the recommended dose of protein.
If, in fact, protein was as fattening as some people assert,
bodybuilders who eat that much would look like walking versions of the
Goodyear blimp. Clearly, they do not. Plus, bodybuilders are
nutritionally savvy enough to boost their protein during dieting
conditions—which also should be hindering their fat loss but clearly
does not. Even people who don’t engage in weight training often eat more
protein than they need, yet they rarely, if ever, get fat—unless they
eat too many carbs and calories along with the protein.
How can that be? For one thing, the usual fate of ingested protein
differs between inactive and active people. In active people excess
protein undergoes metabolic changes in which the nitrogen portion is
removed and excreted as urea. What about the calories?
In active people the excess calories in protein are oxidized in the liver and not stored as fat.
While there is an outside chance that excess protein can wind up as
fat in sedentary folks, in reality, they also have to be overeating
carbs and calories in relationship to their activity levels. That was
shown in a recent highly publicized study published in the prestigious
Journal of the American Medical Association.
1
Twenty-five healthy men and women, aged 18 to 35, all of whom were
overweight to varying degrees, stayed in a metabolic unit in a research
lab for 10 to 12 weeks. First, they ate a “weight-stabilizing” diet—15
percent protein, 25 percent fat and 60 percent carbs— for 13 to 25 days,
and during the last eight weeks they were randomly divided into three
diet groups:
• 5 percent protein (low protein)
• 15 percent protein (normal protein)
• 25 percent protein (high protein)
It wasn’t just the protein intake that the researchers were looking
at, however. All three groups were purposely overfed during the last two
months of the study—specifically, they got 40 percent more calories
than what they ate on the baseline, or maintenance, diet. The results
showed that those in the low-protein group gained less weight than the
others, but they also stored 90 percent of their excess calories as fat.
The 6.6 percent increase in resting metabolism in the low-protein group
was attributed to the metabolic cost of converting the excess calories
into bodyfat. In contrast, in the normal and higher protein groups 50
percent of the excess calories were stored as fat. The rest were burned
up in a thermogenic reaction.
Another difference was that neither resting energy expenditure or
lean body mass increased in the low-protein group, but they did in the
normal- and high-protein groups. The excess calories eaten by all three
groups were in the form of fat, which contains the greatest
concentration of calories. Despite that,
the high-protein group had the least amount of excess calories stored as fat, which underscores the effects of that strategy, as discussed above—that is,
more calories are dissipated during a higher protein intake.
Based on the results of this study, the authors say that overall
calorie intake, not how much protein you eat, is what makes you fat. In
addition, it should be noted that the subjects did not exercise but
rather remained sedentary in a metabolic lab. Without question, vigorous
exercise changes the way nutrients are used in the body. Not only does
exercise burn off excess calories, but the muscle gains accrued during
weight training will prevent any possibility of excess protein being
converted into bodyfat.
—Jerry Brainum
Editor’s note: Have you been ripped off by supplement makers
whose products don’t work as advertised? Want to know the truth about
them? Check out
Natural Anabolics, available at
JerryBrainum.com.
1 Bray, G., et al. (2012). Effect of dietary protein
content on weight gain, energy expenditure, and body composition during
overeating.
JAMA. 307;47-55.
©,2015 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited
Have you been ripped off by supplement makers whose products don’t
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