What are the problems associated with low-carb diets, and do the benefits outweigh the risks?
I want to make it fundamentally clear from the outset that I am NOT suggesting that we eat no carbohydrates, or an "all meat and eggs" diet. So eat your veggies!! The foods I am suggesting we all remove from the diet are the ones that we didn't eat 10,000 years ago, like products that contain sugar, flour, processed grain like white rice, and alcohol (the body treats alcohol like sugar). These are the foods that cause the biggest insulin response. Sugar drives insulin, which drives fat deposition. Vegetable oils are also a brand new food that entered our diet less than 100 years ago and need to be avoided, but that is not a part of this low-carb discussion. Those that are sensitive to carbs may also need to limit or avoid starchy below ground veggies, fruit and whole grains at least until weight and blood sugar are under control. At that point, these healthy foods can be added back in very gradually up to the level tolerated before weight starts to increase again.
Last week's tip on fat accumulation was over-simplistic, and dealt only with fat accumulation where poor blood-sugar control is the driver. Someone who gets fat due to poor blood-sugar control tends to put fat on all over - fat ankles and wrists, fat neck, fat legs and arms, and trunk. But some people put on fat in the hips and legs and are quite slender, sometimes even emaciated in the upper body, a pattern commonly seen in women. This fat pattern is probably more driven by imbalances in estrogen/progesterone, although insulin may play a role. Then there is the big gut, skinny legs and arms pattern, quite common in men. I think cortisol plays a role in this pattern (also food allergy/sensitivity and gut dysbiosis), although blood sugar control is also important. But the bottom line is that much of the time, fat deposition is hormone driven, not calorie driven in my opinion. (I'm not saying that chronic overeating is not a cause of obesity, but rather that people do commonly become over-fat without overeating.) Use functional testing to correct the hormone imbalances, enable the body to lose the fat.
Okay. Back to the low-carb safety question. The health concerns raised with respect to low carb diets are:
The benefits of a low-carb diet are:
In my opinion, if a low carb diet decreases blood sugar, insulin, triglycerides, bad cholesterol, blood pressure, body weight, body inflammation, and increases good cholesterol, that would indicate a lessened risk of heart disease, not an increased one.
In trying to back up the increased risk of stomach / intestinal cancer from a low carb diet, I found studies that indicated that processed and salted meat were a problem. I found one study that indicated that red meat consumption increased the risk of gastric cancer, but I was unable to determine whether the animals consumed were grass-fed or grain-fed. Although I can't back this up with studies, my feeling would be that if the meat consumed is from animals that are eating their natural diet, it is less likely to create a problem. Also it looks like it is an interaction between the ulcer-causing bacteria H. Pylori and the meat that increased the risk of gastric cancer more than red meat alone.
There are lots of studies that seem to indicate that high protein diets can be damaging to the kidneys, in particular through the production of AGEs (Advanced Glycation Endproducts). But by definition AGES are actually glycated proteins, or the bonding of a sugar with a protein. So, is it the high protein or the high blood-sugar that is the real culprit here? AGEs are formed in greater numbers if meat is cooked at high temperatures, so lightly cooking meat may be a viable way to reduce the risk. Low carbohydrate diets do not necessarily mean a huge increase in protein intake in the absolute sense, but rather an increase of percentage of calories from protein relative to carbohydrate.
As for the idea that diets high in protein cause calcium leaching which may lead to osteoporosis, I actually see more evidence to the contrary in my cursory search. Many studies seem to indicate that higher protein levels are important for bone preservation, especially in the elderly who may be malnourished. This review published in the Journal of the American College of Nutrition examines the claims of the dangers of high protein intake on bone mass, and lays them all to rest.
Even studies that show positive results always end with the caveat that it is too early to advocate long term use of low carb diets, as the long term studies have not yet been done. Does the fact that humankind has been eating low starch/low sugar diets for all time up until a couple of centuries ago not count? Although there are some problems with low starch diets, I think they can be very helpful for those trying to lose weight, type 2 diabetics, and those with blood-sugar regulation issues. I think that for many, high starch diets can be far less healthy than low starch diets, but to suggest that everyone needs to follow an Atkin's style diet would be an exaggeration, as long as the food consumed is whole and unprocessed. It will be interesting to see what the long-term studies show.
If you decide to try a low starch /no sugar diet, check with your doctor, particularly if you have health concerns like diabetes, and watch for negative reactions that might indicate you have pushed your metabolism too far - lethargy, constipation, feel full but hungry, heavy gut, mentally sluggish, inability to do the physical activity you are accustomed to doing (the reduction in glycogen stores will cause this), suddenly painful menstruation etc. Make sure that your protein source is real food, and not protein powders etc. If you are having negative reactions, increase the ratio of above-ground vegetables to protein/fat, and make sure you are consuming half your bodyweight in pounds, in ounces of pure water each day, and see if you feel better. If this still doesn't resolve the problem, add whole grains or starchy veggies one tablespoon per meal at a time, until you feel great. Sugar, flour products, processed grains (like white rice) and alcohol however, are not good for anyone and should not be consumed at all, in my opinion.
I look forward to your comments on my blog.
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Taubes, Gary Good Calories, Bad Calories, Challenging the Conventional Wisdom on Diet, Weight Control, and Disease Alfred A. Knopf, New York, 2007.
Chek, Paul; You Are What You Eat CD Series Chek Institute, San Diego, CA, 2002.
A. Adam-Perrot et al. Low-carbohydrate diets: nutritional and physiological aspects Obesity Reviews Volume 7 Issue 1 Page 49-58, February 2006
Westman EC et al. Low-carbohydrate nutrition and metabolism Am J Clin Nutr. 2007 Aug;86(2):276-84.
Campbell PT et al. Dietary patterns and risk of incident gastric adenocarcinoma. Am J Epidemiol. 2008 Feb 1;167(3):295-304. Epub 2007 Nov 28.
Tsugane S et al Diet and the risk of gastric cancer: review of epidemiological evidence. Gastric Cancer. 2007;10(2):75-83. Epub 2007 Jun 25.
González CA et al. Meat intake and risk of stomach and esophageal adenocarcinoma within the European Prospective Investigation Into Cancer and Nutrition (EPIC). J Natl Cancer Inst. 2006 Mar 1;98(5):345-54.
Norat T et al. Meat, fish, and colorectal cancer risk: the European Prospective Investigation into cancer and nutrition. J Natl Cancer Inst. 2005 Jun 15;97(12):906-16.
Jaime Uribarri and Katherine R. Tuttle Advanced Glycation End Products and Nephrotoxicity of High-Protein Diets Clin J Am Soc Nephrol 1: 1293-1299, 2006.
Valerie A. Luyckx and Tara A. Mardigan High protein diets may be hazardous for the kidneys Nephrology Dialysis Transplantation 2004 19(10):2678-2679
Anssi H. Manninen High-protein diets are not hazardous for the healthy kidneys Nephrology Dialysis Transplantation 2005 20(3):657-658
Walser M. Effects of protein intake on renal function and on the development of renal disease. In: The Role of Protein and Amino Acids in Sustaining and Enhancing Performance. Committee on Military Nutrition Research, Institute of Medicine. Washington, DC: National Academies Press, 1999, pp. 137–154
Turner N et al. Excess lipid availability increases mitochondrial fatty acid oxidative capacity in muscle: evidence against a role for reduced fatty acid oxidation in lipid-induced insulin resistance in rodents. Diabetes. 2007 Aug;56(8):2085-92. Epub 2007 May 22.
Huang MC et al. Inadequate energy and excess protein intakes may be associated with worsening renal function in chronic kidney disease. J Ren Nutr. 2008 Mar;18(2):187-94.
Wardak J et al. Analysis of the intake of protein and energy by predialysis patients with chronic renal failure receiving essential amino acid ketoanologues. Rocz Panstw Zakl Hig. 2007;58(1):153-8.
de Andrade AS et al. Relation between diet protein and calciuria in children and adolescents with nephrolitiasis Acta Cir Bras. 2005;20 Suppl 1:242-6.
Jean-Philippe Bonjour, MD Dietary Protein: An Essential Nutrient For Bone Health Journal of the American College of Nutrition, Vol. 24, No. 90006, 526S-536S (2005)
Devine A et al. Protein consumption is an important predictor of lower limb bone mass in elderly women.
Wengreen HJ et al. Dietary protein intake and risk of osteoporotic hip fracture in elderly residents of Utah. J Bone Miner Res. 2004 Apr;19(4):537-45. Epub 2004 Feb 9.
Bonjour JP et al. Nutritional aspects of hip fractures. Bone. 1996 Mar;18(3 Suppl):139S-144S.
Copyright 2008 Vreni Gurd
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