Malingering’s World

I was reading this article What if bad fat isn’t so bad? onMSNBC today and I started to wonder, what if carbs aren’t so bad either?

This carbs and insulin thing really makes my brain spin. Everywhere you look, it says that carbs raise your insulin and insulin makes you fat. There are dozens of health and nutrition books out claiming this point, even in this article above which is challenging the lack of scientific data in common nutrition wisdom like bad fats causing heart disease. So I thought I’d do some searching on this data.

It appears most articles and books (including Barry Sears in The Zone) use this study to show that eating a lot of carbs increases your insulin level. Coulston AM, Liu GC, Reaven GM. Plasma glucose, insulin and lipid responses to high-carbohydrate low-fat diets in normal humans. Metabolism. 1983 Jan;32(1):52-6. Here’s the abstract.

Two levels of dietary carbohydrate (40% and 60% of calories) were incorporated into typical U.S. diets and fed for 10 days each to 11 healthy volunteers. Fasting blood samples were drawn on days 8, 9, and 10 of each dietary period and analyzed for glucose, insulin, cholesterol, triglyceride (TG) and high density lipoprotein (HDL)-cholesterol concentrations. In addition, plasma glucose, insulin and TG concentrations were determined before, and for 3 hr after the noon meal on days 8 and 10. No differences were observed in fasting plasma glucose, insulin or cholesterol concentrations. However, fasting plasma TG levels were significantly elevated on the 60% carbohydrate diet, and HDL-cholesterol concentrations were significantly decreased. Furthermore, the plasma insulin and triglyceride responses to the meal tolerance test during the 60% carbohydrate dietary period were significantly elevated. These results indicate that high-carbohydrate diets lead to changes in insulin, TG, and HDL-cholesterol concentrations which have been associated with an increase in incidence of coronary artery disease.

Wait, what? Eleven subjects? Seriously? People are basing entire theories and books and diet plans on a study from 1983 that used 11 people?

Well there’s this study done a few years later in 1987 with a whopping 14 subjects - GA Spiller, CD Jensen, TS Pattison, CS Chuck, JH Whittam and J Scala. Effect of protein dose on serum glucose and insulin response to sugars. American Journal of Clinical Nutrition, Vol 46, 474-480, 1987. This is the abstract.

To clarify the effects of protein on insulin and glucose response to sugars, 14 healthy normal-weight males and females were fed test meals containing 0, 15.8, 25.1, 33.6, and 49.9 g protein along with approximately 58 g carbohydrate. Serum samples were obtained at fasting time zero and 15, 30, 60, and 120 min postprandial. Mean areas of the glucose curves above fasting decreased with increasing protein dose. Protein-containing meals produced significantly lower (p less than 0.01) areas than the protein-free meal and the relationship between blood glucose area and protein dose was significant (p less than 0.001). Protein-containing meals produced significantly greater (p less than 0.01) insulin areas compared with the protein-free meal. However, no differences in insulin areas among the protein-containing meals were observed. These data support previous studies showing a blood glucose moderating and insulin-enhancing effect of protein ingestion.

Wait. So protein containing meals produced MORE insulin? Am I reading that right? This study was questioned by a research group (since blood levels were drawn only two hours after eating), and in 1990 (three years later) this came out. SA Westphal, MC Gannon and FQ Nuttall. Metabolic response to glucose ingested with various amounts of protein. American Journal of Clinical Nutrition, Vol 52, 267-272.

Seven healthy, normal-weight subjects were fed breakfasts of 50 g protein, 50 g glucose, and 10, 30, or 50 g protein plus 50 g glucose in random sequence. Plasma glucose, insulin, C peptide, glucagon, nonesterified fatty acids, and alpha-amino nitrogen were then measured from samples obtained over 4 h. The postmeal net area of each response curve was calculated. Ingestion of 50 g protein alone did not change the serum glucose concentration. The various amounts of protein ingested with 50 g glucose also did not alter the serum glucose response compared with that observed with 50 g glucose alone. Ingestion of the various amounts of protein also did not result in a further increase in insulin concentration when ingested with glucose, except with the 50-g-protein dose. This increase was modest. Ingestion of glucose resulted in a decrease in alpha-amino nitrogen and glucagon concentrations whereas ingestion of protein increased them as expected. Additions of progressively larger amounts of protein to the glucose meal resulted in a progressive increase in the alpha-amino-nitrogen- and glucagon-area responses. The relationship was curvilinear for both the alpha-amino-nitrogen response and the glucagon response. The null point, that is, the protein dose ingested with 50 g glucose at which there would be no change in area response, was estimated to be 9 g protein for alpha-amino nitrogen and 5 g protein for glucagon.

Okay, am I reading this right? Basically there’s no difference? Adding carbs to your protein (regardless of amount or ratio) will have the same effect on your insulin:glucagon ratio as eating the carbs alone. The only way to keep your insulin down low is to eat no carbs at all (no fruits, no veggies, nothing).

There have been numerous studies comparing high-protein diets and high-carb diets and they pretty much all say the same thing, that the improvement in insulin and glucose levels correlate with the amount of weight you lose, and that’s it. (There’s lot more info on HDL/LDL/TGs but I don’t feel like getting into that right now.)

Medscape General Medicine study 2006. 8 weeks: no difference between high-carb and high-protein diet

Applied Physiology, Nutrition and Metabolism 2007. Article states that High-density lipoprotein cholesterol, fasting blood glucose, and fasting insulin levels were unaltered by diet or exercise.

American Journal of Clinical Nutrition October 2007, comparison of a “carbohydrate rich” and a “protein rich” diet: At the end of the study, all the components of the metabolic syndrome (except HDL, which did not change) decreased significantly in both groups.

The Journal of the American Dietetic Association did a study of people eating a high carb vs. high protein diets and found that
In the high-carbohydrate group, hemoglobin A1c decreased, fasting plasma glucose decreased, and insulin sensitivity increased.

That’s the opposite of what everyone’s been saying, right? Fuck I’m confused. Someone’s going to call me a smart ass, because that’s what always happens, but I really just want an answer to this question:

Do carbs deserve this bad rap?

I’ll leave you with this article by a Dr. McDougall which I found somewhat amusing as he confronts Barry Sears face to face. Apparently you can buy copies of this debate, which is utterly ridiculous, but hey, I give him props for asking questions because really, I’m just trying to do the same thing.

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