It’s commonly assumed that the body uses carbs for fuel and nothing more. That assumption is wrong. It fails to recognize the main biological functions of carbs, which go far beyond just being a substrate for energy. Due to the current popularity of low-carb diets, people often fail to understand that carbs are critical to the full activation of a vital growth-promoting metabolic pathway. The pentose phosphate pathway plays essential roles in the production of steroid hormones and the rate of tissue regeneration and growth as well as disease prevention. Most important, its actions depend solely on the consumption and use of dietary carbs. The Pentose Phosphate Pathway and Its Related Functions
The pentose phosphate pathway is an anabolic process that occurs mostly in the liver and uses pentose (a five-carbon sugar) that comes from glucose (a six-carbon sugar). Its primary functions are to provide ribose-5 phosphate for the synthesis of DNA, RNA and all energy molecules, including ATP and NADPH, which are needed for all metabolic functions, including growth. In addition, the pathway is a precursor of the production of UDP via the glucuronic acid pathway, which is essential for overall detoxification, the transport of steroid hormones, the production of proteoglycan and glycoproteins and the synthesis of sphingolipids (lipids that are necessary for neural protection).
The Adverse Effects of Low-Calorie and Low-Carb Diets
As noted, the pentose phosphate pathway controls critical metabolic functions. When the body desperately needs energy, however, such as during a prolonged fast or a low-calorie, low-carb diet, the pathway shuts down its main functions and switches to sheer energy production. In fact, 30 percent of glucose oxidation in the liver can occur via the pentose phosphate pathway. It’s likely that energy demand is a top priority for the body; so when it’s desperate for energy, the body suppresses certain important functions to accelerate immediate energy production.
Furthermore, since the synthesis of glucose from protein or fat’the process known as gluconeogenesis’is a limited metabolic process that occurs mostly in the liver, it’s reasonable to conclude that, for active individuals in particular, severe low-carb diets, which chronically restrict carb consumption to less than 100 grams per day, may suppress the pentose phosphate pathway due to insufficient glucose supply and increased energy demand.
Also keep in mind that the pentose phosphate pathway’s actions decrease with age, a fact that may contribute to the decline in steroid hormone production, muscle waste, increased vulnerability to disease and reduced energy production. What’s more, it’s important to note that insulin sensitivity is also necessary for optimum glucose use and the full activation of the pentose phosphate pathway.
As you can see, the body uses dietary carbs for a lot more than just energy production. Chronic carb or calorie restriction may help you lose fat in the short run, but in the long run it may diminish critical metabolic processes required for growth, tissue repair, toxin removal and overall energy generation.
Bodybuilders and other athletes should never overlook the important role of carb utilization in muscular development and overall performance. Nevertheless, the question remains:
How can you eat carbs in a way that maximizes all their beneficial effects without causing insulin resistance or fat gain?
Here are some tips:
‘Avoid prolonged low-calorie or crash diets. You want to give your body sufficient energy for optimum function of the pentose phosphate pathway to support steroid hormone synthesis, the activation of growth factors and overall detox.
‘Avoid chronic carb overrestriction, such as you get when you’re on a very-low-carb (less than 100 grams per day) or no-carb ketogenic diet. Not getting enough carbs may adversely affect the pentose phosphate pathway and its related functions, which, as mentioned above, include synthesis of DNA, RNA and ATP necessary for repair and growth as well as the production of proteoglycans. Since proteoglycans are needed for connective tissues, cellular communication and cognitive functions, it’s no wonder you can’t think straight when you’re on a low-carb diet.
‘Try limiting your carb consumption to one meal per day, preferably at night. That way you may be able to confine the high insulin sensitivity to the end of the day and so have optimum carb utilization.
‘Try cycling between days of low carbs and days of moderate-to-high carbs. That can be a highly effective technique for protecting against insulin resistance and preventing fat gain while maximizing carb use for overall regeneration of tissue and energy. For instance, you can incorporate a high-carb day followed by two days of low carbs and higher fat, followed by a moderate-carb day, followed by a low-carb/high-protein day and so on. ALL ‘Minimize your consumption of simple carbs, and always choose complex carbs that have a low glycemic index and are naturally high in fiber. The best choices for carbs are legumes, roots, squashes, barley, oats and wild rice. Whole complex-carb foods release glucose at a slower rate than simple-carb foods and therefore can give your body better glucose utilization with a lowered risk of insulin resistance and blood sugar fluctuation.
‘Do not eat higher-glycemic carbs on their own, particularly grains or roots. Always combine carbs with protein or fat to minimize their glycemic effect. Eaten on their own, carbs may provoke an insulin spike and resulting low blood sugar, bringing symptoms such as dizziness, fatigue, irritability, headaches and a craving for sweets. Bodybuilders and other athletes should carefully design their preworkout and recovery meals to feature a high ratio of protein to carbs.
‘It’s okay to eat low-glycemic whole fruits such as apples, berries or kiwis on an empty stomach. Nonetheless, you may want to squeeze lime or lemon juice on them. Acid slows the rate of carb absorption. The fiber in whole fruits significantly reduces the sugar impact and effectively enhances overall detox.
‘Take multivitamin and multimineral supplements as well as essential fatty acids to facilitate optimum assimilation of all essential nutrients. A shortage of even one essential nutrient may lead to severe metabolic impairment and compromise your body’s ability to use glucose and generate energy. B-vitamins, in particular, are precursors for co-enzymes, which are vital for glucose and energy use. Antioxidants are necessary for protection against free radicals. Note that active people need to increase essential nutrients and antioxidant intake because they eat more than the average person and so produce more free radicals.
Carbs are indeed a double-edged sword; however, as there is so much confusion these days regarding what and how much to eat, it’s important to present another way of looking at carbohydrate-rich foods. They are a viable source of conditionally essential glucose as well as fiber, minerals, oils and phytonutrients. Carbs add unique taste, smell and aroma to food and are considered the cleanest and most digestible fuel’and don’t dismiss the importance of smell, taste and overall satiety. Hunger and satiety mark the presence of powerful neuropeptides that, aside from regulating feeding cycles, also regulate hormonal secretion, sleep-awake cycles, aggression and relaxation, regeneration of tissues, overall energy expenditure and rate of fat burning.
Use your instincts and common sense. Through trial and error you can find the amount of carbs that your body needs. Using old dietary methods such as carb depletion followed by carb loading will enable you to take in a large amount of carbs periodically without gaining fat.
Regardless of what many low-carb advocates say, the human body is well programmed to ingest and use carbs. Therefore, chronically overrestricting or avoiding carbs may be biologically perceived by the body as a suppression of a primal need. When you go against nature, your body may come back with a vengeance to reclaim what was taken away from it, and it will do that by inducing an excruciating hunger with a chronic craving for sweets that often leads to compulsive binging on carbs and undesirable fat gain.
Editor’s note: People suffering from diabetes and blood-sugar-related problems should consult their physician or health professional before adopting any dietary regimen.
Ori Hofmekler is the author of the books The Warrior Diet and Maximum Muscle & Minimum Fat, published by Dragon Door Publications (www.dragondoor.com). For more information or consultations: [email protected], www.warriordiet.com or by phone at 1-866-WAR-DIET. IM