In Carbs Part I: The Weight-Loss Industry’s Biggest Lie, I explained why carbs won’t be the end of our species. Recall that high-fat diets lead to more diabetic cases than high-carb diets, low-carb diets can lead to decreases in immunity, and low-carb diets are the most difficult to sustain. I’m afraid we’ve slumped into the bad habit of blaming carbs for obesity. A correlative: do Q-Tips puncture ear drums, or do reckless ear-wranglers with Q-Tips puncture ear drums? Don’t blame the tool; blame the fool. A barbaric earhole stabber violating the sacred space of the tympanic membrane with a Q-Tip should be convicted by a jury of his peers. But in the hands of a responsible, hygiene-loving auricle technician, Q-Tips are gentle swabs. Likewise, carbs are necessary for health, but carbs abused will destroy health. Controlling and managing carbs are great ideas but, the carb-versus-no-carb debate has cornered us into a false choice. In Part II, I want to explain the proper care and non-criminal use of carbs.
Why Should I Eat Carbs?
You’ve heard of simple and complex carbs. Maybe even sugary, starchy, and fibrous. The three official classes of carbs are polysaccharides, disaccharides, and monosaccharides—all to tell you what you already knew: carbs can be simple or complex or somewhere in between.
In a typical meal, polysaccharides make up 60 to 70 percent of total carbs and cover anything you would consider a starchy or fibrous carbohydrate. Simple carbs—like table sugar—begin at the disaccharide level. Monosaccharides are more of a biochemical designation and are the end result of digestion. Even pouring Pixie Stix powder down your throat would be ingesting a disaccharide. I know, those were the days….
Here’s where that begins to matter. Typical digestion time for most carb meals is 30 to 40 minutes in the stomach. Some digestion occurs in the small intestine due to chyme secretions, but blood sugar levels elevate almost immediately after consumption and will begin to peak after half an hour.
You probably think I’m going to pull out the Glycemic Index and lecture you on eating responsibly with complex carbs to slow down digestion, avoid blood sugar spikes, and all that jazz. Let’s fast forward past the rookie stuff.
How Are Carbs Digested?
Your body reduces any carb source into monosaccharides and unusable refuse. Glucose hits the bloodstream and efficiently feeds tens of trillions of cells. The fibrous carbs that are passed through are repurposed in your large intestine like an old barn on the DIY Network. But, instead of a nice coffee table, anaerobic bacteria turn that indigestible cellulose into fat to be used as energy. We didn’t get to the top of the food chain by wasting energy! Technically speaking, this process of glycolysis is the digestion of polysaccharides (or disaccharides) into monosaccharides, transportation to cells, and cell transfer of energy into ADP to form ATP. Then pyruvate enters anaerobic respiration (when oxygen is limited or absent) or aerobic respiration (Krebs Cycle) and then into oxidative phosphorylation and the electron transport chain. So, there.
Why is that important? We don’t simply have the ability to use carbs, we evolved to prefer them for specific reasons. The speed and efficiency of which we can turn them into energy is critical for survival. Of course we can turn fat and protein into energy, but options provide advantages—fast movement required as hunter and hunted (carbs) and unplanned fasting (fat/protein). Evolution is a fine, fine filter of proficiency. Sharks might be bigger and cheetahs might be faster, but we hold the remote control, baby!
But Low-Carb Diets Still Work Better, Right?
Gluconeogenesis is our way back out of storage. It’s how we retrieve energy. We can synthesize new glucose from carbs (pyruvate, lactate), fat (glycerol), or muscle (the amino acids alanine or glutamine). Of course we want use as much from stored fat as possible, and none from muscle, but it’s a matter of degrees. Carbs prime the pump. Carbs drive metabolism. In a study of more than 4,000 people, the thinnest ate the most carbs and the most overweight consumed the fewest. This is anecdotal, but the sheer volume should raise eyebrows.
Need a more rigorously controlled study? How about an inpatient setting where subjects could only eat what was fed to them instead of relying on self-reporting? Talk about raising eyebrows. That kind of research is rare, if not almost impossible to come by! But, Kevin Hall, a senior researcher at the National Institutes of Health, did just that when comparing low-carb and low-fat diets. His team conducted significant sampling of biological processes instead of merely reading the number on a bathroom scale. I’ll let him do the talking: “In contrast to previous claims about a metabolic advantage of carbohydrate restriction for enhancing body fat loss, our data and model simulations support the opposite conclusion.”
Isn’t it fun when even scientists are surprised by science? It takes an open mind. Like a thumb tack, paint sprayer, or Ferrari, a gummy bear can help you or end you—just tools. We’ll survey more research in Part III to sort out what method of dieting stands alone as the champion!