An implication of the current research on self-regulation is to implement the promotion of self-regulated learning in schools. Teachers can promote self-regulated learning either directly by teaching learning strategies or indirectly by arranging a learning environment that enables students to practise self-regulation. This study investigates teachers' direct and indirect promotion of self-regulated learning and its relation to the development of students' performance. Twenty German mathematics teachers with their overall 538 students (grade 9) were videotaped for a three-lesson unit on the Pythagorean Theorem. Students' mathematics performance was tested several times before and after the observed lessons. A low-inferent coding system was applied to assess the teachers' implicit or explicit instruction of cognitive strategies (e.g., organisation), metacognitive strategies (e.g., planning), and motivational strategies (e.g., resource management). High-inferent ratings were used to assess features of the learning environment that foster self-regulation. Results reveal that a great amount of strategy teaching takes place in an implicit way, whereas explicit strategy teaching and supportive learning environment are rare. The instruction of organisation strategies and some features of the learning environment (constructivism, transfer) relate positively to students' performance development. In contrast to implicit strategy instruction, explicit strategy instruction was associated with a gain in performance. These results reveal a discrepancy between the usefulness of explicit strategy instruction and its rare occurrence in classrooms.

The orexigenic and anabolic gastric hormone ghrelin is secreted in response to acute and chronic energy requirements. While pre-prandial increases and post-prandial decreases of plasma ghrelin levels in rodents and humans seem to indicate a role for the novel peptide hormone as an afferent meal initiator or "hunger hormone", the precise mechanisms which are suppressing ghrelin secretion in response to caloric intake remain largely unknown. We show here that human ghrelin levels decrease by almost 50% under hyperinsulinemic euglycemic clamp conditions (no.=4, p=0.001), revealing physiologically relevant increases of insulin levels as an independent determinant of circulating ghrelin levels. In a second study, 3-4-fold increased plasma free fatty acid levels, as another metabolic candidate for the modulation of circulating ghrelin concentrations, were generated by constant lipid infusion, but failed to change plasma ghrelin. Simultaneous elevation of free fatty acids and insulin again markedly decreased ghrelin concentration (no.=4, p=0.01). Insulin induced suppression of circulating ghrelin levels (or the lack thereof) could be a mechanism with relevance for the understanding of the (patho-) physiology of meal initiation and termination, the pathogenesis of the metabolic syndrome and for the development of respective therapeutic perspectives.

Brennan IM, Luscombe-Marsh ND, Seimon RV, Otto B, Horowitz M, Wishart JM, Feinle-Bisset C. Effects of fat, protein, and carbohydrate and protein load on appetite, plasma cholecystokinin, peptide YY, and ghrelin, and energy intake in lean and obese men. Am J Physiol Gastrointest Liver Physiol 303: G129 -G140, 2012. First published April 30, 2012 doi:10.1152/ajpgi.00478.2011.-While protein is regarded as the most satiating macronutrient, many studies have employed test meals that had very high and unsustainable protein contents. Furthermore, the comparative responses between lean and obese subjects and the relationships between energy intake suppression and gut hormone release remain unclear. We evaluated the acute effects of meals with modest variations in 1) fat, protein, and carbohydrate content and 2) protein load on gastrointestinal hormones, appetite, and subsequent energy intake in lean and obese subjects. Sixteen lean and sixteen obese men were studied on four occasions. Following a standardized breakfast, they received for lunch: 1) high-fat (HF), 2) high-protein (HP), 3) high-carbohydrate/low-protein (HC/LP), or 4) adequateprotein (AP) isocaloric test meals. Hunger, fullness, and gut hormones were measured throughout, and at t ϭ 180 min energy intake at a buffet meal was quantified. In lean subjects, hunger was less and fullness greater following HF, HP, and AP compared with HC/LP meals, and energy intake was less following HF and HP compared with HC meals (P Ͻ 0.05). In the obese subjects, hunger was less following HP compared with HF, HC/LP, and AP meals, and energy intake was less following HP and AP compared with HF and HC meals (P Ͻ 0.05). There were no major differences in hormone responses to the meals among subject groups, but the CCK and ghrelin responses to HP and AP were sustained in both groups. In conclusion, HP meals suppress energy intake in lean and obese subjects, an effect potentially mediated by CCK and ghrelin, while obese individuals appear to be less sensitive to the satiating effects of fat. diet composition; obesity; protein intake; dietary macronutrients; gut hormone release THE CURRENT AVERAGE WESTERN diet derives ϳ50% of energy from carbohydrate, 35% from fat, and 15% from protein (35), which represents a shift toward an increased carbohydrate and reduced protein intake when compared with the diet of our hunter-gatherer ancestors (14). Of the dietary macronutrients, protein is generally regarded as the most satiating nutrient. Accordingly, one dietary strategy for the management of obesity has been to replace some carbohydrate in the diet with protein (2,19,49), although the benefit of this approach remains uncertain (24,29,48). A recent study indicated that in obese subjects weight regain after a 26-wk period was less (by 930 g) in response to a high-protein diet (25% energy from protein), compared with a low-protein diet (13% energy from protein) (29). There is little definitive information about the comparative effects of the three macronutrients or differences in protein l...

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Our findings do not support a role for abnormal circulating PYY in human obesity. We conclude that circulating PYY levels in humans are significantly elevated in anorexia nervosa and, given the controversially discussed anorectic effect of PYY, could theoretically contribute to that syndrome.