The effects of a protein-rich breakfast on glucose metabolism in overweight/obese late adolescent girls

"May 2014."Thesis advisor: Dr. Heather J. Leidy.Background: Skipping breakfast has been associated with an increased risk of type II diabetes and obesity. Purpose: To examine the effects of normal protein vs. higher protein breakfast meals on pre- and post-lunch glycemic control in overweight/obese adolescents who either habitually skip breakfast vs. adolescents who habitually consume high CHO breakfast meals. Methods: Thirty--five overweight/obese teen girls participated in the following randomized crossover--design study. The participants were grouped according to habitual breakfast frequency. The habitual breakfast skipping group randomly completed the following breakfast patterns at home for 3 days: 1) Breakfast Skipping (BS); 2) Normal Protein (NP) breakfast; and 3) High Protein (HP) breakfast. The habitual breakfast consuming group randomly completed the NP and HP breakfast patterns at home for 3 days. On day 4 of each pattern (for both groups), the participants complete the respective 8--h testing day. The respective breakfast was provided at the beginning of the day and a NP lunch was provided 4h post--breakfast. Blood samples were collected at specific times throughout the day for plasma insulin and glucose responses. Results: The addition of breakfast led to increased morning glucose and insulin responses vs. BS (both, P < 0.05). When comparing the normal protein vs. high protein breakfast meals, the post--lunch glycemic response was different between the meals but was significantly modulated by the frequency of habitual breakfast consumption. The breakfast skippers experienced lower afternoon and total glucose concentrations following the normal protein breakfast but higher afternoon and total glucose concentrations following the high protein breakfast compared to the breakfast consumers (both, P < 0.05). Minimal differences in afternoon and/or total insulin were detected between meals or between groups. Conclusion: These data suggest that the addition of breakfast, regardless of protein content, has very little effect on post--lunch glycemic contrIncludes bibliographical references (pages 37-41)

Examination of Protein Quantity and Protein Distribution across the Day on Ad Libitum Carbohydrate and Fat Intake in Overweight Women

BACKGROUND: The effects of meal-specific protein quantity and protein distribution throughout the day on daily food intake are relatively unknown. OBJECTIVES: The aims were to test 1) whether the consumption of higher-protein (HP) compared with normal-protein (NP) meals consumed at each eating occasion reduce free-living, daily carbohydrate and fat intakes in overweight women during energy balance conditions and 2) whether the distribution of protein consumed throughout the day affects food intake outcomes. METHODS: Seventeen women [mean ± SEM age: 33 ± 1 y; body mass index (in kg/m2): 27.8 ± 0.1] completed the following tightly controlled, crossover design study. Participants were provided with and randomly consumed three 6-d eucaloric diets containing NP or HP (15% or 25% of energy as protein, respectively). The protein content within the NP diet used an even distribution pattern (EVEN; 21 ± 1 g protein/meal) throughout the day, whereas the protein contents within the HP diets used either EVEN (35 ± 1 g protein/meal) or an uneven distribution pattern (UNEVEN; 19 ± 1 g protein/breakfast, 26 ± 1 g protein/lunch, 63 g protein/dinner). On day 7 of each diet, the participants were asked to consume the diet-specific absolute protein quantity (in grams) at each eating occasion but were provided with a surplus of carbohydrate- and fat-rich foods to consume, ad libitum, during each eating occasion. RESULTS: Eating more protein (HP compared with NP) or evenly distributing protein throughout the day (HP-EVEN compared with HP-UNEVEN) did not reduce the consumption of ad libitum fat- and carbohydrate-rich foods throughout the day (NP-EVEN: 2850 ± 240 kcal/d; HP-EVEN: 2910 ± 240 kcal/d; HP-UNEVEN: 3160 ± 200 kcal/d). Despite the lack of differences in daily energy intake, the breakfast meal within the HP-EVEN diet led to lower ad libitum carbohydrate and fat intakes than the breakfast meals in the NP-EVEN and HP-UNEVEN diet conditions (P &lt; 0.05). CONCLUSION: Providing 30 g protein/meal at each eating occasion throughout the day did not influence free-living, daily intake of highly palatable, carbohydrate- and fat-rich foods in overweight women. This trial was registered at clinicaltrials.gov as NCT02614729

Examination of Protein Quantity and Protein Distribution across the Day on Ad Libitum Carbohydrate and Fat Intake in Overweight Women

BACKGROUND: The effects of meal-specific protein quantity and protein distribution throughout the day on daily food intake are relatively unknown. OBJECTIVES: The aims were to test 1) whether the consumption of higher-protein (HP) compared with normal-protein (NP) meals consumed at each eating occasion reduce free-living, daily carbohydrate and fat intakes in overweight women during energy balance conditions and 2) whether the distribution of protein consumed throughout the day affects food intake outcomes. METHODS: Seventeen women [mean ± SEM age: 33 ± 1 y; body mass index (in kg/m2): 27.8 ± 0.1] completed the following tightly controlled, crossover design study. Participants were provided with and randomly consumed three 6-d eucaloric diets containing NP or HP (15% or 25% of energy as protein, respectively). The protein content within the NP diet used an even distribution pattern (EVEN; 21 ± 1 g protein/meal) throughout the day, whereas the protein contents within the HP diets used either EVEN (35 ± 1 g protein/meal) or an uneven distribution pattern (UNEVEN; 19 ± 1 g protein/breakfast, 26 ± 1 g protein/lunch, 63 g protein/dinner). On day 7 of each diet, the participants were asked to consume the diet-specific absolute protein quantity (in grams) at each eating occasion but were provided with a surplus of carbohydrate- and fat-rich foods to consume, ad libitum, during each eating occasion. RESULTS: Eating more protein (HP compared with NP) or evenly distributing protein throughout the day (HP-EVEN compared with HP-UNEVEN) did not reduce the consumption of ad libitum fat- and carbohydrate-rich foods throughout the day (NP-EVEN: 2850 ± 240 kcal/d; HP-EVEN: 2910 ± 240 kcal/d; HP-UNEVEN: 3160 ± 200 kcal/d). Despite the lack of differences in daily energy intake, the breakfast meal within the HP-EVEN diet led to lower ad libitum carbohydrate and fat intakes than the breakfast meals in the NP-EVEN and HP-UNEVEN diet conditions (P &lt; 0.05). CONCLUSION: Providing 30 g protein/meal at each eating occasion throughout the day did not influence free-living, daily intake of highly palatable, carbohydrate- and fat-rich foods in overweight women. This trial was registered at clinicaltrials.gov as NCT02614729