Effect of low-glycemic-sugar-sweetened beverages on glucose metabolism and macronutrient oxidation in healthy men.

BACKGROUND/OBJECTIVES: Sugar-sweetened-beverages (SSB) provide high amounts of rapidly absorbable sugar and have been shown to impair insulin sensitivity and promote weight gain. We hypothesized that when compared with high-glycemic index (GI) SSB low-GI SSB lead to lower insulin secretion and thus an improved preservation of insulin sensitivity and fat oxidation during an inactive phase. SUBJECTS/METHODS: In a controlled cross-over dietary intervention 13 healthy men (age: 23.7±2.2 years, body mass index: 23.6±1.9 kg m(-)(2)) consumed low-GI (isomaltulose) or high-GI (75% maltodextrin+25% sucrose, adapted for sweetness) SSBs providing 20% of energy requirement for 7 days. During this phase, participant's habitual high physical activity (11 375±3124 steps per day) was reduced (2363±900 steps per day). The provided ad libitum diet comprised 55% CHO, 30% fat and 15% protein. Glycemic and insulinemic responses were assessed: Day-long (7-day continuous interstitial glucose monitoring, 24-h-urinary c-peptide excretion), during meal test (37 g isomaltulose vs 28 g maltodextrin+9g sucrose) and measures of insulin sensitivity (basal: homeostasis model assessment of insulin resistance (HOMA-IR), postprandial: Matsuda-ISI). Macronutrient oxidation was assessed by non-protein respiratory quotient (npRQ) in the fasted state (npRQfasting) and postprandial as the area under the npRQ-curve during meal test (npRQtAUC-meal). RESULTS: Day-long glycemia was lower with low-GI compared with high-GI SSB (-5%, P<0.05). Low-GI SSB led to lower insulin secretion during meal test (-28%, P<0.01) and throughout the day (-31%, P<0.01), whereas postprandial glucose levels did not differ between low-GI and high-GI SSBs. Insulin sensitivity deteriorated on inactivity with both SSBs, but was better preserved with low-GI isomaltulose compared with high-GI maltodextrin-sucrose (ΔHOMA-IR: +0.37±0.52 vs +0.85±0.86; ΔMatsuda-ISI: -5.1±5.5 vs -9.6±5.1, both P<0.05). Both, fasting and postprandial fat oxidation declined on inactivity, with no difference between high-GI and low-GI SSBs. CONCLUSIONS: Compared with high-GI SSB, 7-day consumption of beverages sweetened with low-GI isomaltulose had beneficial effects on inactivity-induced impairment of glucose metabolism without effecting fuel selection.

Deep body composition phenotyping during weight cycling: relevance to metabolic efficiency and metabolic risk.

Weight cycling may lead to adverse effects on metabolic efficiency (i.e. adaptive thermogenesis or 'metabolic slowing') and metabolic risks (e.g. increased risk for insulin resistance and the metabolic syndrome). In order to investigate these topics, the partitioning of fat and lean mass (i.e. the change in the proportion of both compartments) needs to be extended to the organ and tissue level because metabolic risk differs between adipose tissue depots and lean mass is metabolically heterogeneous being composed of organs and tissues differing in metabolic rate. Contrary to data obtained with severe weight loss and regain in lean people, weight cycling most likely has no adverse effects on fat distribution and metabolic risk in obese patients. There is even evidence for an increased ability of fat storage in subcutaneous fat depots (at the trunk in men and at the limbs in women) with weight cycling that may provide a certain protection from ectopic lipid deposition and thus explain the preservation of a favourable metabolic profile despite weight regain. On the other hand, the mass-specific metabolic rate of lean mass may increase with weight gain and decrease with weight loss mainly because of an increase and respective decrease in the proportion (and/or activity) of metabolically active organ mass. Obese people could therefore have a higher slope of the regression line between resting energy expenditure (REE) and fat-free mass that leads to an overestimation of metabolic efficiency when applied to normalize REE data after weight loss. Furthermore, in addressing the impact of macronutrient composition of the diet on partitioning of lean and fat mass, and the old controversy about whether a calorie is a calorie, we discuss recent evidence in support of a low glycaemic weight maintenance diet in countering weight regain and challenge this concept for weight loss by proposing the opposite.

Carbohydrate intake and glycemic index affect substrate oxidation during a controlled weight cycle in healthy men.

BACKGROUND/OBJECTIVES: Because both, glycemic index (GI) and carbohydrate content of the diet increase insulin levels and could thus impair fat oxidation, we hypothesized that refeeding a low GI, moderate-carbohydrate diet facilitates weight maintenance. SUBJECTS/METHODS: Healthy men (n=32, age 26.0±3.9 years; BMI 23.4±2.0 kg/m(2)) followed 1 week of controlled overfeeding, 3 weeks of caloric restriction and 2 weeks of hypercaloric refeeding (+50, -50 and +50% energy requirement) with low vs high GI (41 vs 74) and moderate vs high CHO intake (50% vs 65% energy). We measured adaptation of fasting macronutrient oxidation and the capacity to supress fat oxidation during an oral glucose tolerance test. Changes in fat mass were measured by quantitative magnetic resonance. RESULTS: During overfeeding, participants gained 1.9±1.2 kg body weight, followed by a weight loss of -6.3±0.6 kg and weight regain of 2.8±1.0 kg. Subjects with 65% CHO gained more body weight compared with 50% CHO diet (P<0.05) particularly with HGI meals (P<0.01). Refeeding a high-GI diet led to an impaired basal fat oxidation when compared with a low-GI diet (P<0.02), especially at 65% CHO intake. Postprandial metabolic flexibility was unaffected by refeeding at 50% CHO but clearly impaired by 65% CHO diet (P<0.05). Impairment in fasting fat oxidation was associated with regain in fat mass (r=0.43, P<0.05) and body weight (r=0.35; P=0.051). CONCLUSIONS: Both higher GI and higher carbohydrate content affect substrate oxidation and thus the regain in body weight in healthy men. These results argue in favor of a lower glycemic load diet for weight maintenance after weight loss.

[An improved method for the radiotherapy of breast carcinoma]. / Eine verbesserte Methode der Strahlentherapie des Mammakarzinoms.

This method of radiotherapy of the breast and lymph nodes in cases of breast cancer reduces exposure of the lung and features small gaps and overlaps at the borders of neighbouring fields. The outline of fields, the design of special absorbing blocks and filters, and some notes on treatment planning are given in this paper.

[Practical experiences and problems with precision testing in direct radiography in a medical center]. / Praktische Erfahrungen und Probleme mit der Konstanzprüfung bei Direktradiographie in einem Schwerpunktkrankenhaus.

This is a report on the practical experience in respect of the monthly testing of the precision (constancy and long-term reproducibility of results) of X-ray film apparatus. The test method described in the German DIN standard No. 6868 Part 3 has even been refined in some points.

Empirical equations for Co-60 scatter-air ratio calculations.

Simple empirical equations have been fitted to recognized tables of scatter-air ratio values for central points of square and circular fields of Cobalt-60 gamma rays with a maximum error of 0.006. From these equations further equations have been developed for scatter-air ratio calculations for off-axis points of rectangular fields and for corner points of triangular fields. The latter can be used in dose calculations for polygonal (irregular) fields. Herewith we have a complete system of equations for all practically important scatter dose calculations for Co-60 teletherapy.

[Calculation of the dosage distributions in intracavitary radium applicators based on measurements of the directional dependence of the dose rate]. / Berechnung von Dosisverteilungen an intrakavitären Radium-Applikatoren aufgrund von Messungen der Richtungsabhängigkeit der Dosisleistung.

A simple method for the calculation of dose distributions around intracavitary radium applicators has been developed. The cylindrical activity distribution of a single radium source is simulated by a row of point sources. The inverse square law for point sources is modified by two factors, one depending on direction and the other on distance, to account for absorption and scatter in the sources, applicator, and tissue. Factors depending on direction for Buchler applicators (intrauterine tubes, round plates, and cones) have been determined from measurements in a water phantom, because the angular dependence of dose rate in tissue differs from that in air owing to the influence of scatter.

[Description of the dose distribution in the radiation field of a teletherapy unit with Co-60 (author's transl)]. / Eine Beschreibung der Dosisverteilung im Strahlungsfeld einer Gammabestrahlungsanlage mit Co-60.

Equations are given for the calculation of dose distributions for teletherapy with Co-60. The distribution of primary radiation in the penumbral region is derived approximately from geometrical data of the source and diaphragm. Empirical formulas are given for the distribution of scattered radiation and for the tissue-air ratio. Constants in the equations were taken from measurements. The influences of source-skin distance, tissue depth, field size, angle of incidence, and penumbra trimmers are taken into account. Nevertheless the calculations do not exceed the capacity of a desk-top computer.

[Calculation of rotating field isodose lines without spike artefacts (author's transl)]. / Berechnung von Pendelfeld-Isodosen ohne Zackenartefakte.

When rotating fields are calculated by addition of a series of fixed fields, the resulting isodose lines often show spike artefacts. To avoid these, the fixed fields can be substituted by real rotating field increments. Significant differences between fixed fields and rotating field increments are found only in the penumbral region, where the smearing effect of the rotation makes the slope less steep. A method is introduced for the calculation of dose distributions in rotating field increments using a "smeared penumbral function".