|Will the additional butter on top of the potatoes reduce the insulin response? You can find the answer to this and the other questions in today's episode of "True or False?"|
Adding Fat to A Meal Will Ameliorate the Insulin ResponseFalse. When you are browsing the Internet it is easy to get the impression that what is wrong or right is not determined by scientific evidence, but by the number of people who repeat it in their blogs, on their facebook walls and in their bulletin board contributions. The common "wisdom" that it would be a good idea to add some fat to a meal to reduce the insulin spike it will give you is one of those paradigms that remain intrinsically flawed no matter how often they are repeated.
GIP Or Not GIP - That is the Question: "Fat intake, in addition to ingestion of carbohydrate, stimulates GIP release. Therefore, during a mixed meal GIP might act to promote the storage of both triglyceride and glucose indirectly via the release of insulin." (Kieffer. 2003)The amount of the fat storage peptide GIP (learn more), on the . Therefore, Collier and O'Dea are 100% right, when they state in the conclusion of their 1983 paper that...
"despite the apparent improvement in glucose tolerance when carbohydrate is ingested together with fat, the accompanying potentiation of insulin secretion could form the basis of long-term changes in insulin sensitivity which accompany alterations in dietary fat intake." (Collier. 1983)You may want to remember that, whenever you feel inclined to add a ton of bacon on top of your sweet potatoes in the false believe that this would "mitigate" the effects of the carb-laden tubers the insulin response.
This obviously does not change the fact that having some fat in a meal does have the added benefit of increasing GLP-1 and PYY levels and thus contributing to a longer satiety effect (eg. Knut. 2008)
Skeletal Muscle Hypertrophy Impairs Oxygen Diffusion
|"Some HIIT For Life & Less LISS For More!" As the study at hand shows, this mantra is all the more important for the more muscular SuppVersity readers - that does not change that exercising longer to burn more fat won't work for anyone, muscular or not (learn why).|
I have to admit that the 15-20% reduction in maximal oxygen consumption per kg of quadriceps mass a group of researchers from the University of Udine observed in 11 young athletes with marked skeletal muscle hypertrophy induced by long-term resistance training (body mass ~103kg), when they compared their them to 11 normal controls (body mass ~77kg) looks scary at first.
If you do yet also take into consideration that this decrease in oxygenation was accompanying improvements in ADP-stimulated mitochondrial respiration (+59%; takes place, when the ATP stores are used up) and a tighter coupling of oxidative phosphorylation, it becomes evident that the training induced enhancements in mitochondrial respiration seem to compensate for the hypertrophy-induced impaired peripheral O2 diffusion.
"The net results are an enhanced whole body oxidative function at peak exercise, and unchanged efficiency and O2 cost at submaximal exercise, despite a much greater body mass." (Salvadego. 2013)In other words, despite "suboptimal" oxygenation of the musculature a bigger metabolic engine will still burn more fat... but only when it's working at peak intensity. It won't do so at submaximal intensities, where the O2 costs are "identical" (statistically). So, what does that tell us about the usefulness of training in the non-existent fat burning zone for advanced, heavily muscled trainees? Yep, it's even smaller than for the average sedentary housewife.
Low Carb High Fat Diets Lead to Acute Improvements in Muscular Insulin SensitivityFalse. Although the slowly abating low-carb craze does still make it appear as if "just eating less carbs" was the solution to everything, it is only logical that low carb dieting leads to changes in skeletal muscle insulin signaling, i.e. decreases in insulin-stimulated tyrosine phosphorylation of IRS-1 and PI3-kinase activity, which reduce, not increase the ability / willingness of the musculature to suck up glucose from the blood stream within no more than 5 days (cf. Pessin. 2000; Reusch. 2002).
|Figure 2: Changes (before vs. after 5-day intervention) in fasting glycemia and lipidemia and glucose rate of appearance and disposal during euglycemic clamp conditions (Wang. 2013)|
"But that ain't low carb!" Certainly a valid critism w/30% carbs and 20% protein in the diet it is practically impossible to reach ketosis, but - believe it or not - this is representative of the "low carb" diets you will usually see in the pertinent literature.Wang et al. base their conclusion on the results of a recently conducted weight loss intervention that involved 18 obese individuals without diabetes who underwent euglycemic-hyperinsulinemic clamp and skeletal muscle biopsy after:
- 5 days of eucaloric diet (30% fat, 50% carbohydrate), and
- 5 days of a 30% calorie-restricted diet, containing either...
- LF/HC: 20% fat, 60% carbs
- HF/LC: 50% fat, 30% carbs.
In other words, "No, 'just eat no carbs' is not the solution to everything", but will lead to certain metabolic adaptations which are not exactly conducive to returning to a normal carb diet afterwards. Plus, if you are a lean gymrat striving to to maximize your lean mass gains the full-blown hepatic growth hormone resistance and corresponding -50% drop in hepatic IGF-1 mRNA expression Bielohuby et al. observed in a rodent model of ketogenic dieting in 2011 probably won't come handy in the long run (on a side note: The "keto rodents", with their 92.8% fat diet also had a 5% reduction in lean mass and 46%, 56% and 223% higher relative amounts of visceral fat in the inguinal, epididymal and perirenal fat pads; cf. Bielohub. 2011)
Keep in mind this is a physiological form of insulin resistance
|Learn how Adelfo lost his carbophobia and saw nothing but benefits from it (read more). That someone in the >30kg/m² BMI region with type II diabetes should keep a close eye on carb intake is a whole different story.|
Would the effect have been different with a true keto diet? The weight loss? Maybe. The transient insulin resistance? More pronounced, if anything. If you are already obese and freakin' insulin resistant to begin with, this does yet hardly matter. Low fat, high fat, keto - I don't care! The weight loss, the ensuing reduction in chronic inflammation and the new room to actually stash away superfluous energy alone will sooner or later also help you to reduce your insulin resistance.
Suggested read on physiological (=adaptation to diet / exercise) insulin resistance: "The Marathon Paradox - How Temporary Exercise-Induced Insulin Resistance Paves the Way for Fat Burning Machines" (complete article)
- Berk ES, Kovera AJ, Boozer CN, Pi-Sunyer FX, Johnson JA, Albu JB. Adiponectin levels during low- and high-fat eucaloric diets in lean and obese women. Obes Res. 2005 Sep;13(9):1566-71.
- Bielohuby M, Sawitzky M, Stoehr BJ, Stock P, Menhofer D, Ebensing S, Bjerre M, Frystyk J, Binder G, Strasburger C, Wu Z, Christ B, Hoeflich A, Bidlingmaier M. Lack of dietary carbohydrates induces hepatic growth hormone (GH) resistance in rats. Endocrinology. 2011 May;152(5):1948-60.
- Collier G, O'Dea K. The effect of coingestion of fat on the glucose, insulin, and gastric inhibitory polypeptide responses to carbohydrate and protein. Am J Clin Nutr. 1983 Jun;37(6):941-4.
- Fraser DA, Thoen J, Bondhus S, Haugen M, Reseland JE, Djøseland O, Førre O, Kjeldsen-Kragh J. Reduction in serum leptin and IGF-1 but preserved T-lymphocyte numbers and activation after a ketogenic diet in rheumatoid arthritis patients. Clin Exp Rheumatol. 2000 Mar-Apr;18(2):209-14.
- Glass DJ. Molecular mechanisms modulating muscle mass. Trends Mol Med. 2003 Aug;9(8):344-50. Review.
- Kieffer TJ. GIP or not GIP? That is the question. Trends Pharmacol Sci. 2003 Mar;24(3):110-2.
- Knuth ND, Shrivastava CR, Horowitz JF. Reducing dietary fat from a meal increases the bioavailability of exogenous carbohydrate without altering plasma glucose concentration. J Appl Physiol. 2009 Jan;106(1):122-9. doi: 10.1152/japplphysiol.90404.2008. Epub 2008 Nov 13.
- Pessin JE, Saltiel AR. Signaling pathways in insulin action:molecular targets of insulin resistance. J Clin Invest. 2000;106(2):165–9.
- Salvadego D, Domenis R, Lazzer S, Porcelli S, Rittweger J, Rizzo G, Mavelli I, Simunic B, Pisot R, Grassi B. Skeletal muscle oxidative function in vivo and ex vivo in athletes with marked hypertrophy from resistance training. J Appl Physiol. 2013 Mar 21.
- Reusch JE. Current concepts in insulin resistance, type 2 diabetes mellitus, and the metabolic syndrome. Am J Cardiol. 2002;90(5A):19G–26G.
- Wang CC, Adochio RL, Leitner JW, Abeyta IM, Draznin B, Cornier MA. Acute effects of different diet compositions on skeletal muscle insulin signalling in obese individuals during caloric restriction. Metabolism. 2013; 62:595–603