Postprandial blood glucose, homones and food intake : A clinical trial

Background: Several aspects of the postprandial effects of meals need further investigation. In particular, we were interested in focusing on whether the glycemic effect of meals is related to the serum concentration of hormones known to be involved in appetite regulation, and to hunger and food intake. Objective/research questions: Will the intake of two lunch meals differing in the carbohydrate source, have different effects on a) the postprandial blood glucose concentration and b) serum levels of hormones related to appetite: insulin, ghrelin, leptin and growth hormone? Will possible differences in these variables be reflected in a) hunger during the next five hours and b) food intake at the next meal? Methods: Eleven overweight male adults were evaluated on two separate occasions in a cross over fashion. The subjects consumed at noon either a meal with an anticipated low or high glycemic effect (meal L and H respectively). The meals were similar in energy and fat content, taste and energy density, but had major differences in carbohydrate sources (lentils or potato as main sources of carbohydrate, respectively). Meal H and L differed also in protein, carbohydrate and fibre content. During five hours after the lunch meal, hunger, plasma blood glucose and serum hormone levels were measured. Five hours after lunch, the ad libitum food intake was determined at a single meal. Results: Glucose levels were remarkably stable after meal L and did not increase by more than 13 % to peak, whereas glucose levels after meal H increased by 52 % to peak and reached a nadir that was 8% lower than baseline values. There were significant differences after the two test meals in plasma ghrelin (H>L), growth hormone (H>L) and insulin concentration (H>L), but no differences in hunger or food intake were observed. Conclusion: Lunch meals with appreciably differing postprandial glycemic effects do not affect hunger or food intake in the next meal in overweight adults in this particular setting, in spite of differences in the serum level of appetite regulating hormones

High-fat diet impact on intestinal cholesterol conversion by the microbiota and serum cholesterol levels

Cholesterol-to-coprostanol conversion by the intestinal microbiota has been suggested to reduce intestinal and serum cholesterol availability, but the relationship between intestinal cholesterol conversion and the gut microbiota, dietary habits, and serum lipids has not been characterized in detail. We measured conserved proportions of cholesterol high and low-converter types in individuals with and without obesity from two distinct, independent low-carbohydrate high-fat (LCHF) dietary intervention studies. Across both cohorts, cholesterol conversion increased in previous low-converters after LCHF diet and was positively correlated with the fecal relative abundance of Eubacterium coprostanoligenes. Lean cholesterol high-converters had increased serum triacylglycerides and decreased HDL-C levels before LCHF diet and responded to the intervention with increased LDL-C, independently of fat, cholesterol, and saturated fatty acid intake. Our findings identify the cholesterol high-converter type as a microbiome marker, which in metabolically healthy lean individuals is associated with increased LDL-C in response to LCHF.publishedVersio

Diets differing in carbohydrate cellularity and amount similarly reduced visceral fat in people with obesity - a randomized controlled trial (CARBFUNC)

publishedVersio

Diets differing in carbohydrate cellularity and amount similarly reduced visceral fat in people with obesity - a randomized controlled trial (CARBFUNC)

Background & aims Visceral adipose tissue (VAT) volume is associated with common lifestyle diseases. Dietary quality, including food matrix and degree of carbohydrate cellularity, as well as the carbohydrate/fat ratio, may influence VAT volume. We aimed to determine the effects of isocaloric diets differing in either “cellularity”, a novel marker of dietary carbohydrate quality, or carbohydrate amount on visceral fat volume and anthropometric measures in adults with obesity. Methods In a randomized controlled trial of 193 people with obesity/central adiposity, we compared changes in VAT volume after 6 and 12 months, measured by abdominal computed tomography, on three isocaloric eating patterns based on “acellular” carbohydrate sources (e.g., flour-based whole-grain products; comparator arm), “cellular” carbohydrate sources (minimally processed foods with intact cellular structures such as fruits, potatoes/tubers, and rice), or low-carbohydrate high-fat (LCHF) principles. Outcomes were compared by an intention-to-treat (ITT) analysis using constrained linear mixed-effects modelling (cLMM) providing baseline-adjusted change scores and proper missing data handling without imputation. Results 78 and 57 participants completed 6 and 12 months, respectively, with similar intakes of energy (females: 1820−2060 kcal, males: 2480−2550 kcal) and protein (16–17 energy percent, E%) throughout the intervention, and only modest reductions in energy from baseline. Reported dietary intakes were 42–44, 41–42, and 11–15 E% carbohydrate and 36–38, 37–38, and 66–70 E% fat in the acellular, cellular and LCHF groups, respectively. There were no significant between-group differences in VAT volume after 6 months (cellular vs. acellular [95% CI]: −55 cm³ [−545, 436]; LCHF vs. acellular [95% CI]: −225 cm³ [−703, 253]) or after 12 months (cellular vs. acellular [95% CI]: −122 cm³ [−757, 514]; LCHF vs. acellular [95% CI]: −317 cm³ [−943, 309]). VAT volume decreased significantly within all groups by 14–18% and 12–17% after 6 and 12 months, respectively. Waist circumference was reduced to a significantly greater degree in the LCHF vs. acellular group at 6 months (LCHF vs. acellular [95% CI]: −2.78 cm [−5.54, −0.017]). Conclusions Despite modest energy restriction, the three isocaloric eating patterns, differing in carbohydrate cellularity and amount, decreased visceral fat volume significantly and to a similar clinically relevant degree