Wednesday, November 23, 2016
Quality protein intake is inversely related with abdominal fat
Abstract
Dietary
protein intake and specifically the quality of the protein in the diet
has become an area of recent interest. This study determined the
relationship between the amount of quality protein, carbohydrate, and
dietary fat consumed and the amount of times the ~10 g essential amino
acid (EAA) threshold was reached at a meal, with percent central
abdominal fat (CAF). Quality protein was defined as the ratio of EAA to
total dietary protein. Quality protein consumed in a 24-hour period and
the amount of times reaching the EAA threshold per day was inversely
related to percent CAF, but not for carbohydrate or dietary fat. In
conclusion, moderate to strong correlations between variables indicate
that quality and distribution of protein may play an important role in
regulating CAF, which is a strong independent marker for disease and
mortality.
Introduction
Dietary
protein intake and specifically the quality of the protein in the diet
has become an area of recent interest, particularly when combined with
resistance training (for a thorough review the reader is directed to
ref. [1]).
Quality of protein is defined as the ratio of essential amino acids
(EAA) to dietary protein in grams. The dietary reference intake (DRI)
includes no specific recommendation regarding the type of dietary
protein consumed or distribution of that dietary protein throughout the
day. Approximately 10 g of EAA, at a meal, maximally stimulates muscle
protein synthesis (MPS) [2]. EAA intake beyond this level does not appear to result in an additional anabolic response [3].
Studies
have demonstrated that the consumption of dietary protein above the DRI
has been associated with favorable changes in body composition [4]. Proposed mechanisms include the maintenance or accretion of lean mass and/or increased thermogenesis and satiety [5]. A 5-year prospective study found that protein intake was inversely related to changes in waist circumference [6].
Waist circumference is a surrogate marker for abdominal obesity, and
this type of obesity is associated with significant risks of developing
type 2 diabetes, coronary artery disease, stroke, and a higher risk of
mortality, even after adjustments for general obesity [6].
However, the quality of the protein source consumed and the
distribution of that protein throughout the day with respect to central
abdominal fat (CAF) have not been investigated in free living
conditions.
We
sought to determine the relationship between the amount of quality
protein consumed in 24-hours and the amount of times the ~10 g EAA
threshold was reached at a meal, with respect to percent CAF. This is a
secondary analysis using a data set from a previously reported paper on
quality protein, overall body composition (lean mass and total body
fat), and bone health [7].
Weight loss maintenance in overweight subjects on ad libitum diets with high or low protein content and glycemic index: the DIOGENES trial 12-month results
Abstract
BACKGROUND:
A high dietary protein (P) content and low glycemic index (LGI) have been suggested to be beneficial for weight management, but long-term studies are scarce.OBJECTIVE:
The DIOGENES randomized clinical trial investigated the effect of P and GI on weight loss maintenance in overweight or obese adults in eight centers across Europe. This study reports the 1-year results in two of the centers that extended the intervention to 1 year.METHOD:
After an 8-week low-calorie diet (LCD), 256 adults (body mass index >27 kg m(-)(2)) were randomized to five ad libitum diets for 12 months: high P/LGI (HP/LGI), HP/high GI (HP/HGI), low P/LGI (LP/LGI), LP/HGI and a control diet. During the first 6 months, foods were provided for free through a shop system and during the whole 12-month period, subjects received guidance by a dietician. Primary outcome variable was the change in body weight over the 12-month intervention period.RESULTS:
During the LCD period, subjects lost 11.2 (10.8, 12.0) kg (mean (95% confidence interval (CI))). Average weight regain over the 12-month intervention period was 3.9 (95% CI 3.0-4.8) kg. Subjects on the HP diets regained less weight than subjects on the LP diets. The difference in weight regain after 1 year was 2.0 (0.4, 3.6) kg (P=0.017) (completers analysis, N=139) or 2.8 (1.4, 4.1) kg (P<0.001) (intention-to-treat analysis, N=256). No consistent effect of GI on weight regain was found. There were no clinically relevant differences in changes in cardiometabolic risk factors among diet groups.CONCLUSION:
A higher protein content of an ad libitum diet improves weight loss maintenance in overweight and obese adults over 12 months.High protein intake sustains weight maintenance after body weight loss in humans
Abstract
BACKGROUND:
A relatively high percentage of energy intake as protein has been shown to increase satiety and decrease energy efficiency during overfeeding.AIM:
To investigate whether addition of protein may improve weight maintenance by preventing or limiting weight regain after weight loss of 5-10% in moderately obese subjects.DESIGN OF THE STUDY:
In a randomized parallel design, 148 male and female subjects (age 44.2 +/- 10.1 y; body mass index (BMI) 29.5 +/- 2.5 kg/m2; body fat 37.2 +/- 5.0%) followed a very low-energy diet (2.1 MJ/day) during 4 weeks. For subsequent 3 months weight-maintenance assessment, they were stratified according to age, BMI, body weight, restrained eating, and resting energy expenditure (REE), and randomized over two groups. Both groups visited the University with the same frequency, receiving the same counseling on demand by the dietitian. One group (n=73) received 48.2 g/day additional protein to their diet. Measurements at baseline, after weight loss, and after 3 months weight maintenance were body weight, body composition, metabolic measurements, appetite profile, eating attitude, and relevant blood parameters.RESULTS:
Changes in body mass, waist circumference, REE, respiratory quotient (RQ), total energy expenditure (TEE), dietary restraint, fasting blood-glucose, insulin, triacylglycerol, leptin, beta-hydroxybutyrate, glycerol, and free fatty acids were significant during weight loss and did not differ between groups. During weight maintenance, the 'additional-protein group' showed in comparison to the nonadditional-protein group 18 vs 15 en% protein intake, a 50% lower body weight regain only consisting of fat-free mass, a 50% decreased energy efficiency, increased satiety while energy intake did not differ, and a lower increase in triacylglycerol and in leptin; REE, RQ, TEE, and increases in other blood parameters measured did not differ.CONCLUSION:
A 20% higher protein intake, that is, 18% of energy vs 15% of energy during weight maintenance after weight loss, resulted in a 50% lower body weight regain, only consisting of fat-free mass, and related to increased satiety and decreased energy efficiency.A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations
Abstract
Background: Ad libitum, low-carbohydrate diets decrease caloric intake and cause weight loss. It is unclear whether these effects are
due to the reduced carbohydrate content of such diets or to their associated increase in protein intake.
Objective: We tested the hypothesis that increasing the protein content while maintaining the carbohydrate content of the diet lowers
body weight by decreasing appetite and spontaneous caloric intake.
Design: Appetite, caloric
intake, body weight, and fat mass were measured in 19 subjects placed
sequentially on the following diets:
a weight-maintaining diet (15% protein, 35% fat,
and 50% carbohydrate) for 2 wk, an isocaloric diet (30% protein, 20%
fat,
and 50% carbohydrate) for 2 wk, and an ad libitum
diet (30% protein, 20% fat, and 50% carbohydrate) for 12 wk. Blood was
sampled
frequently at the end of each diet phase to measure
the area under the plasma concentration versus time curve (AUC) for
insulin,
leptin, and ghrelin.
Results: Satiety was
markedly increased with the isocaloric high-protein diet despite an
unchanged leptin AUC. Mean (±SE) spontaneous
energy intake decreased by 441 ± 63 kcal/d, body
weight decreased by 4.9 ± 0.5 kg, and fat mass decreased by 3.7 ± 0.4 kg
with the ad libitum, high-protein diet, despite a
significantly decreased leptin AUC and increased ghrelin AUC.
Conclusions: An increase
in dietary protein from 15% to 30% of energy at a constant carbohydrate
intake produces a sustained decrease
in ad libitum caloric intake that may be mediated
by increased central nervous system leptin sensitivity and results in
significant
weight loss. This anorexic effect of protein may
contribute to the weight loss produced by low-carbohydrate diets.
Postprandial thermogenesis is increased 100% on a high-protein, low-fat diet versus a high-carbohydrate, low-fat diet in healthy, young women.
Abstract
OBJECTIVE:
The recent literature suggests that high-protein, low-fat diets promote a greater degree of weight loss compared to high-carbohydrate, low-fat diets, but the mechanism of this enhanced weight loss is unclear. This study compared the acute, energy-cost of meal-induced thermogenesis on a high-protein, low-fat diet versus a high-carbohydrate, low-fat diet.METHODS:
Ten healthy, normal weight, non-smoking female volunteers aged 19-22 years were recruited from a campus population. Using a randomized, cross-over design, subjects consumed the high-protein and the high-carbohydrate diets for one day each, and testing was separated by a 28- or 56-day interval. Control diets were consumed for two days prior to each test day. On test day, the resting energy expenditure, the non-protein respiratory quotient and body temperature were measured following a 10-hour fast and at 2.5-hour post breakfast, lunch and dinner. Fasting blood samples were collected test day and the next morning, and complete 24-hour urine samples were collected the day of testing.RESULTS:
Postprandial thermogenesis at 2.5 hours post-meal averaged about twofold higher on the high protein diet versus the high carbohydrate diet, and differences were significant after the breakfast and the dinner meals (p < 0.05). Body temperature was slightly higher on the high protein diet (p = 0.08 after the dinner meal). Changes in the respiratory quotient post-meals did not differ by diet, and there was no difference in 24-hour glomerular filtration rates by diet. Nitrogen balance was significantly greater on the high-protein diet compared to the high-carbohydrate diet (7.6 +/- 0.9 and -0.4 +/- 0.5 gN/day, p < 0.05), and at 24-hour post-intervention, fasting plasma urea nitrogen concentrations were raised on the high protein diet versus the high-carbohydrate diet (13.9 +/- 0.9 and 11.2 +/- 1.0 mg/dL respectively, p < 0.05).CONCLUSIONS:
These data indicate an added energy-cost associated with high-protein, low-fat diets and may help explain the efficacy of such diets for weight loss.Gluconeogenesis and energy expenditure after a high-protein, carbohydrate-free diet.
Abstract
BACKGROUND:
High-protein diets have been shown to increase energy expenditure (EE).OBJECTIVE:
The objective was to study whether a high-protein, carbohydrate-free diet (H diet) increases gluconeogenesis and whether this can explain the increase in EE.DESIGN:
Ten healthy men with a mean (+/-SEM) body mass index (in kg/m(2)) of 23.0 +/- 0.8 and age of 23 +/- 1 y received an isoenergetic H diet (H condition; 30%, 0%, and 70% of energy from protein, carbohydrate, and fat, respectively) or a normal-protein diet (N condition; 12%, 55%, and 33% of energy from protein, carbohydrate, and fat, respectively) for 1.5 d according to a randomized crossover design, and EE was measured in a respiration chamber. Endogenous glucose production (EGP) and fractional gluconeogenesis were measured via infusion of [6,6-(2)H(2)]glucose and ingestion of (2)H(2)O; absolute gluconeogenesis was calculated by multiplying fractional gluconeogenesis by EGP. Body glycogen stores were lowered at the start of the intervention with an exhaustive glycogen-lowering exercise test.RESULTS:
EGP was lower in the H condition than in the N condition (181 +/- 9 compared with 226 +/- 9 g/d; P < 0.001), whereas fractional gluconeogenesis was higher (0.95 +/- 0.04 compared with 0.64 +/- 0.03; P < 0.001) and absolute gluconeogenesis tended to be higher (171 +/- 10 compared with 145 +/- 10 g/d; P = 0.06) in the H condition than in the N condition. EE (resting metabolic rate) was greater in the H condition than in the N condition (8.46 +/- 0.23 compared with 8.12 +/- 0.31 MJ/d; P < 0.05). The increase in EE was a function of the increase in gluconeogenesis (DeltaEE = 0.007 x Deltagluconeogenesis - 0.038; r = 0.70, R(2) = 0.49, P < 0.05). The contribution of Deltagluconeogenesis to DeltaEE was 42%; the energy cost of gluconeogenesis was 33% (95% CI: 16%, 50%).CONCLUSIONS:
Forty-two percent of the increase in energy expenditure after the H diet was explained by the increase in gluconeogenesis. The cost of gluconeogenesis was 33% of the energy content of the produced glucose.
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