In this 2-phase randomized controlled study, we examined whether consuming a higher-protein (HP) diet would attenuate fat-free mass (FFM) loss during energy deficit (ED) at high altitude (HA) in 17 healthy males (mean 6 SD: 23 6 6 yr; 82 6 14 kg). During phase 1 at sea level (SL, 55 m), participants consumed a eucaloric diet providing standard protein (SP; 1.0 g protein/kg,) for 21 d. During phase 2, participants resided at HA (4300 m) for 22 d and were randomly assigned to either an SP or HP (2.0 g protein/kg) diet designed to elicit a 40% ED. Body composition, substrate oxidation, and postabsorptive whole-body protein kinetics were measured. Participants were weight stable during SL and lost 7.9 6 1.9 kg (P < 0.01) during HA, regardless of dietary protein intake. Decrements in wholebody FFM (3.6 6 2.4 kg) and fat mass (3.6 6 1.3 kg) were not different between SP and HP. HP oxidized 0.95 6 0.32 g protein/kg per day more than SP and whole-body net protein balance was more negative for HP than for SP (P < 0.01). Based on changes in body energy stores, the overall ED was 70% (21849 6 511 kcal/d, no group differences). Consuming an HP diet did not protect FFM during severe ED at HA.-Berryman, C. E., Young, A. J., Karl, J. P., Kenefick, R. W., Margolis, L. M., Cole, R. E., Carbone, J. W., Lieberman, H. R., Kim, I.-Y., Ferrando, A. A., Pasiakos, S. M. Severe negative energy balance during 21 d at high altitude decreases fat-free mass regardless of dietary protein intake: a randomized controlled trial. FASEB J. 32, 894-905 (2018 For lowlanders sojourning at high altitude (HA .1500 m), maintaining energy balance can be challenging because of an increase in resting metabolic rate (RMR) (1, 2) and a decrease in appetite (3) caused by physiologic adaptations to hypoxia. The effects of hypoxia on energy balance are frequently compounded by limited access to food and high physical activity levels while at HA. Negative energy balance usually develops at HA and typically leads to weight loss (4). Barnholt et al. (4) showed that individuals sustaining a 40% energy deficit (ED) for 21 d at HA lost more body weight than individuals adhering to the same controlled diet and physical activity at sea level (SL). Furthermore, some studies (5-8) have observed .50% of total body mass (TBM) loss as fat-free mass (FFM) during prolonged ED at HA, which is greater than the 25-35% typically observed at SL (9-11), suggesting protein turnover kinetics and substrate utilization during weight loss at HA may differ from that at SL.At SL, protein intake above the Recommended Dietary Allowance (RDA, 0.8 g protein/kg per day) limits FFM loss during moderate negative energy balance (;40% ED) in healthy, normal weight adults (12)(13)(14). We have shown that consuming a diet containing 1.6 or 2.4 g protein/kg per day (2 and 3 times the RDA, respectively) for 21 d, within the context of a 40% ED, attenuates FFM loss as a percentage of TBM loss (30 6 7 and 36 6 5%, respectively) compared to an isocaloric diet containing 0.8 g protein/kg per d...

BackgroundEvidence consistently shows that almond consumption beneficially affects lipids and lipoproteins. Almonds, however, have not been evaluated in a controlled‐feeding setting using a diet design with only a single, calorie‐matched food substitution to assess their specific effects on cardiometabolic risk factors.Methods and ResultsIn a randomized, 2‐period (6 week/period), crossover, controlled‐feeding study of 48 individuals with elevated LDL‐C (149±3 mg/dL), a cholesterol‐lowering diet with almonds (1.5 oz. of almonds/day) was compared to an identical diet with an isocaloric muffin substitution (no almonds/day). Differences in the nutrient profiles of the control (58% CHO, 15% PRO, 26% total fat) and almond (51% CHO, 16% PRO, 32% total fat) diets were due to nutrients inherent to each snack; diets did not differ in saturated fat or cholesterol. The almond diet, compared with the control diet, decreased non‐HDL‐C (−6.9±2.4 mg/dL; P=0.01) and LDL‐C (−5.3±1.9 mg/dL; P=0.01); furthermore, the control diet decreased HDL‐C (−1.7±0.6 mg/dL; P<0.01). Almond consumption also reduced abdominal fat (−0.07±0.03 kg; P=0.02) and leg fat (−0.12±0.05 kg; P=0.02), despite no differences in total body weight.ConclusionsAlmonds reduced non‐HDL‐C, LDL‐C, and central adiposity, important risk factors for cardiometabolic dysfunction, while maintaining HDL‐C concentrations. Therefore, daily consumption of almonds (1.5 oz.), substituted for a high‐carbohydrate snack, may be a simple dietary strategy to prevent the onset of cardiometabolic diseases in healthy individuals.Clinical Trial RegistrationURL: www.clinicaltrials.gov; Unique Identifier: NCT01101230.

The apparently smaller LDL cholesterol (LDL-C)-lowering effect of soy in recent studies has prompted the U.S. FDA to reexamine the heart health claim previously allowed for soy products. We therefore attempted to estimate the intrinsic and extrinsic (displacement) potential of soy in reducing LDL-C to determine whether the heart health claim for soy continues to be justified. The intrinsic effect of soy was derived from a meta-analysis using soy studies (20-133 g/d soy protein) included in the recent AHA Soy Advisory. The extrinsic effect of soy in displacing foods higher in saturated fat and cholesterol was estimated using predictive equations for LDL-C and NHANES III population survey data with the substitution of 13-58 g/d soy protein for animal protein foods. The meta-analysis of the AHA Soy Advisory data gave a mean LDL-C reduction of 0.17 mmol/L (n = 22; P < 0.0001) or 4.3% for soy, which was confirmed in 11 studies reporting balanced macronutrient profiles. The estimated displacement value of soy (13-58 g/d) using NHANES III population survey data was a 3.6-6.0% reduction in LDL-C due to displacement of saturated fats and cholesterol from animal foods. The LDL-C reduction attributable to the combined intrinsic and extrinsic effects of soy protein foods ranged from 7.9 to 10.3%. Thus, soy remains one of a few food components that reduces serum cholesterol (>4%) when added to the diet.

The majority of the US population exceeds minimum recommendations for protein intake. Protein intake remains well below the upper end of the AMDR, indicating that protein intake, as a percentage of energy intake, is not excessive in the American diet. This trial was registered at www.isrctn.com as ISRCTN76534484.