Are Diets High In Carbohydrates Making You Fat? Part II

I wrote an article last year that was one of my more popular entries.  Why?  Probably because it was about carbohydrates; every journalists favourite macronutrient to take a giant crap on.  This is going to be the second part of the series with a twist.  Seeing as many people bitch about confirmation bias (and rightfully so) I am going to play the devils advocate on this bitch (for a bit), and attempt to cherry-pick some studies that will backup my findings on how insulin and anything related to increasing insulin can and will make you a fat person.

Let’s first take a look at what insulin does in the body before we move on to those juicy studies.  Basically insulin is a hormone released by the pancreas, which regulates fat and carbohydrate metabolism.  Insulin is required to store carbohydrates in the liver, skeletal muscle, and fat tissue.  It is stored as glycogen in the liver and skeletal muscle and as triglycerides in fat tissue.  Insulin inhibits lipolysis (fat loss).  Reducing quantities of carbs eaten, generally does good things to biomarkers of health: decreased triglycerides, decreased cholesterol, decreased LDL-C, and increased HDL-C.

Let’s start with the children.  A study completed on children and adolescent sought out to “assess the metabolic abnormalities and its association with hsCRP in obese children and adolescents.”  First let’s quickly get this hsCRP bidness out of the way.  It means high-sensitivity C-reactive protein, which is a marker of inflammation, which characterizes the atherosclerotic process.  This study isn’t technically about insulin per se, but does cover certain symptoms of a highly insulinogenic diet.

So, what were the symptoms of these children and adolescents with a higher BMI and blood pressure than the control group?  The study showed the usual suspects of metabolic syndrone: increased triglycerides, increased cholesterol, increased LDL-C, decreased HDL-C.  They also showed an increase in hsCRP, or an increase in inflammation. Predictably , the researchers also noticed an increase in homeostatic model assessment-insulin resistance a.k.a the larger subjects had higher levels of insulin resistance than the normal weight children.

The Sensationalist-Journalist Takeaway: Make sure you keep your insulin resistance to a minimal so you won’t get fat.

Let’s take a look at the Glycemic Index.  Check this article out to learn a little more about the GI.  I have always wanted to see what real life results could come about using the GI.  Well this study attempted something along those lines.  They wanted to find out how meals utilizing foods with different GI’s would affect an obese persons eating behaviour before eating an ad libitum meal after the high or medium GI meal.  They concluded with the 12 obese subjects they used that a high GI meal resulted in a “sequence of hormonal and metabolic changes that promote excessive food intake in obese subjects.”  Voluntary energy intake after the high GI meal was 28% more than the medium GI meal.

The Sensationalist-Journalist Takeaway: Stay away from high GI foods that promote insulin gainz, otherwise you will overeat and become another statistic.

I compared some high and low carbohydrate diets in my first article but let’s take a look at one more.  A study by Samaha et al looked at the results of a low carbohydrate (LC) diet on weight loss and risk factors for athersclerosis.  The researchers used a high-carb (HC) diet (500 cal/d deficit w/ 30% of fat or less), and a low carb diet (30g CHO/d max with no restriction on fat, ergo no calorie regulation).  After 6 months the HC dieters lost 1.9 kg, while the LC dieters lost 5.8 kg.  More predictably the LC group had a greater decrease in mean triglyceride levels.  Oddly enough total cholesterol, HDL, and LDL levels did not change significantly between groups which contradicts numerous other studies.  Who cares, we’ll leave that part out.

The Sensationalist-Journalist Takeaway: Whoa!!! Score one for low carbers with no confounding variables…

What parts of “insulin is fattening” can we take away from the studies above?

  • Increased levels of insulin resistance are associated with obesity.
  • Foods, which are high in GI (which can increase insulin) result in an increased energy intake.
  • Low carb diets result in increased fat loss.

**I’m aware of the generalizations I’ve made from the studies above.  However, if you actually look at the research cited by some of these low-carb gurus, these are the generalizations they take away from studies with similar results.  So don’t bitch**

Now, let me be me.  Let’s peep some research.

Sure we can agree that increased increased insulin resistance is associated with obesity.  Remember, this is an association (like watching Reality TV shows are associated with a low IQ).  Meaning that insulin resistance is associated with obesity, not that insulin resistance causes obesity, which is becoming dogma among the “carbohydrates are bad” sheep.

Unfortunately these gurus forget to mention how exercise can also improve biomarkers of health regardless of bodyfat.  A study at the University of South Carolina checked out 43,000 obese subjects.  Metabolically healthy subjects were grouped if they had 0 or 1 of the criteria for metabolic syndrome. This is what they found: “When adjusting for fitness and other confounders, metabolically healthy but obese individuals had lower risk (30–50%, estimated by hazard ratios) of all-cause mortality, non-fatal and fatal cardiovascular disease, and cancer mortality than their metabolically unhealthy obese peers; while no significant differences were observed between metabolically healthy but obese and metabolically healthy normal-fat participants.”

Yes, the end part can be quite an eye opener.  These individuals had no significant difference with metabolically healthy normal-fat participants.  This goes to show how important exercise can be in preventing, or reversing the symptoms of metabolic syndrome.  Not only can symptoms be erased or reduced, but you can live just as long  (if not longer) as a normal weight laze-ass.

Just so we’re all on the same page.  It’s possible for people to be obese and have healthy bio-marker of health and live a long and prosperous life.  These obese people have regular levels of fasting insulin despite being obese.

Now onto the GI.  We know that foods that are low on the GI can still have high scores on the insulin index.  So let’s look at how foods that have a high GI effect hunger and fat loss.  Believe it or not, increasing levels of insulin also increase levels of leptin (a hormone, which increases metabolic activity, and reduces hunger).

Raatz et al created a study to try and test their hypthoses than a hypocaloric diet with a low GI and low glycemic load (GL) was superior than other diets at sustaining fat loss.  Well, their hypothesis was incorrect: “Weight loss and improved insulin sensitivity scores were independent of diet composition. In summary, lowering the glycemic load and glycemic index of weight reduction diets does not provide any added benefit to energy restriction in promoting weight loss in obese subjects.”

A systematic review was conducted by Raben on the effects of a low GI diet on appetite, food intake, energy expenditure and bodyweight by .  Here is what he concluded:

  • In 31 short-term studies (<1 day), low-GI foods were associated with reducing hunger in 15 studies, whereas reduced satiety or no differences were seen in 16 other studies.
  • Low-GI foods reduced ad libitum food intake in seven studies, but not in eight other studies
  • In 20 long studies (lasting less than 6 months), weight loss on a low-GI diet was seen in four, and on a high-GI diet in two, with no differences recorded in 14.  Average weight loss in the low-GI groups was 1.5kg and on the high-GI groups 1.6kg respectively.
  • “To conclude, there is no evidence at present that low-GI foods are superior to high-GI foods in regard to long-term body weight control. However, the ideal long-term study where ad libitum intake and fluctuations in body weight are permitted, and the diets are similar in all aspects except GI, has not yet been performed.”

Lets quickly look at how high-carb diets effect hunger and satiety compared to other types of diets.

A group of researchers checked out how a large breakfast with a high-fat (HF), high-protein (HP), or high-carbohydrate (HC) composition would effect hunger, and energy intake for a ad libitum meal 5 hours after breakfast.  The HF meal resulted in the largest subjective feeling of hunger compared to the HC and HP meals.  However, during the ad libitum meals, energy intake (EI) was similar in all three test groups.  On top of that, 24 hour EI was also similar in all three control groups.  So the HC group did not in fact result in increased hunger 5 hours later compared to the HF and HP group.  This is just one study, but I found numerous studies using similar designs that came up with the same conclusion.

Another study found that HC meals actually had a higher satiating effect than  a HF meal, which I find pretty damn amusing.  Anecdotally, I agree with this as well, I find meals high in carbs and fibre to be highly satiating.

Part I of this series pretty much debunked the third point I have on here, which is that low-carbohydrate diets are superior to high carbohydrate diets for fat loss.  This is simply not true and tosses the notion that calories matter out of the window, and into a steaming pile of horseshit.  There is no evidence that a diet which manipulates carbohydrates can expedite the fat burning process, unless you want to cherry pick poorly designed studies (and you will still have problems finding them).

I will leave you with a few tidbits of knowledge:

  • The human body can hold ~500 grams of carbohydrates in the liver and muscles.  Each gram of glycogen (storage form of carbohydrates) carry 3-4 grams of water.  Therefore, you can hold up to 2kg of water at any time.  A low carb diet will deplete your glycogen stores resulting in quick loss of water (not bodyfat).  So if you hear that low carb diets are better than high(er) carb diets you can write that person an angry e-mail, leave a burning bag of shit on their doorstep, or egg their house.
  • Calories reign supreme for fat loss.  If you want to lose weight, create a calorie deficit by eating less food, or increasing your caloric expenditure, or any combination.  If you don’t care about muscle loss, the composition of your diet doesn’t matter as long as your calorie intake is under your caloric expenditure. I’ve said that so many times, and I’ll probably keep repeating myself…
  • If losing muscle is as unacceptable to you as the reported remake of Roadhouse, then you need to jack up your protein intake whilst dieting.  Low-carb, high-carb, low-fat, high-fat, high-bacon, high-cheesecake, whatever diet you’re on, make sure you’re getting at least 1g/lb of protein.  This is probably far more (like double) what you are used to, but do it.

That’s all folks.