|This is what it's all about. Real food does not come in form of "macros". It comes in form of complex food matrices that determine its effect on one's health - including one's glycemic health.|
You don't remember this or any of the other articles? Well, in that case, I probably have to tell you again that the mere fact that the postprandial glucose are lower does not mean that a certain food or combination of certain macronutrients would increase your insulin sensitivity (adding fat to a high carbohydrate meal certainly doesn't do that, believe me).
While this is possible for certain supplements like berberine and other AMPK activators, it is mandatory that we differentiate the following three cases:
- Reduced postprandial blood glucose levels in response to an increase in insulin sensitivity as it is triggered by exercise or AMPK activators,
- Reduced postprandial blood glucose levels in response to increased insulin levels as they occur with the co-ingestion with whey protein and
- Reduced postprandial blood glucose levels in response to increased insulin levels and a decreased rate of absorption of glucose as it is the case if you add fat to carbohydrates.
Let's take a look at study design, results and implications
In their study, Wathik Alsalim and his colleagues from the Lund University in Sweden and the Consiglio Nazionale delle Ricerche in Italy investigated the integrative impact of macronutrients on postprandial glycemia, β-cell function, glucagon and incretin hormones in man. The subjects were male and female Caucasian subjects, aged 30-70 years and BMI 20-35 kg/m², without diabetes (normal fasting glucose and normal HbA1c) or with T2D without any pharmacological glucose-lowering therapy and HbA1c <60 mmol/mol (<7.8%).
"Exclusion criteria were liver disease, diabetic nephropathy, proliferative diabetic retinopathy, pregnancy or breast feeding, treatment with oral antidiabetic or insulin, previous myocardial infarction, coronary heart disease or angina pectoris, previous surgery on the gastrointestinal tract, larger surgical intervention the last 12 weeks or treatment with oral steroids or thiazide diuretics" (Alsalim. 2015).Participants were studied at the Lund University's Clinical Research Center on four occasions in a randomized cross-over design, separated by at least four and maximally eight weeks. After overnight-fast (no food after 10pm), subjects were provided with antecubital vein catheter. After two baseline samples at 5, and 2 mins, they ingested in randomized order either one of the macronutrients alone
- glucose - 330kcal = 83g; Skåne University Hospital Pharmacy, Lund, Sweden,
- protein mixture - 110kcal = 30g; ISO WHEY protein consisting of milk and egg protein
- fat emulsion - 110kcal = 24ml; 50% long-chain triglycerides and 50% water;
|Figure 1: To allow for maximal control, the "meal" (macro composition on the right) was a shake (Alsalim. 2015).|
|Both vegetable oils and ghee had identical (beneficial) effects on the starch composition, but they have to be added during boiling or before frying and boiling (Kaur. 2015).|
Unfortunately, the results are less "unique" than the design of the study. (A) Red rice produced a slower digestion rate than white rice. (B) The digestibility of white rice was not affected by oil type, but was affected by addition time of oil, in general. (C) Adding oil “after” (stir-frying) to white or red rice resulted in higher slowly digestible starch. In that, (D) adding the fat before or during cooking and frying respectively had the most significant effect on the subject's postprandial glycemic response and the resistant starch content of the food.
|Figure 2: Glucose and insulin response as well as corresponding insulinogenic index and insulin clearance of the individual macros and the mixed meal - all data expressed relative to the values of 110kcal of glucose (Alsalim. 2015).|
(fat burning) satiety hormone GLP1, which were observed only in the diabetic subjects, though, these changes are yet far more beneficial for the average type II diabetic than they are for the lean athlete, who doesn't need the extra-insulin to maintain normal blood glucose levels and may even consider them an obstacle on his / her way to single-digit body fat levels.
- Alsalim et al. "Mixed meal diminishes glucose excursion compared to glucose by several adaptive mechanisms in man." Diabetes, Obesity and Metabolism (2015): Accepted article.
- 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.
- Hallschmid, Manfred, et al. "Intranasal insulin reduces body fat in men but not in women." Diabetes 53.11 (2004): 3024-3029.
- Kaur B, Ranawana V, Teh AL, Henry CJ. "The Glycemic Potential of White and Red Rice Affected by Oil Type and Time of Addition." J Food Sci. (2015).
- Robertson, R. Paul, et al. "Glucose toxicity in β-cells: type 2 diabetes, good radicals gone bad, and the glutathione connection." Diabetes 52.3 (2003): 581-587.
- Steen, Eric, et al. "Impaired insulin and insulin-like growth factor expression and signaling mechanisms in Alzheimer's disease-is this type 3 diabetes?." Journal of Alzheimer's disease 7.1 (2005): 63-80.