Atrk
Menu
AAEFX Carbs Users Guide Free Download

Maintenance of energy expenditure on high-protein vs. high-carbohydrate diets at a constant body weight may prevent a positive energy balance

Background & aims: Relatively high-protein diets are effective for body weight loss, and subsequent weight maintenance, yet it remains to be shown whether these diets would prevent a positive energy balance. Therefore, high-protein diet studies at a constant body weight are necessary. The objective was to determine fullness, energy expenditure, and macronutrient balances on a high-protein low-carbohydrate (HPLC) diet compared with a high-carbohydrate low-protein (HCLP) diet at a constant body weight, and to assess whether effects are transient or sustained after 12 weeks.

Methods: A randomized parallel study was performed in 14 men and 18 women [mean ± SD age: 24 ± 5 y; BMI (in kg/m2): 22.8 ± 2.0] on diets containing 30/35/35 (HPLC) or 5/60/35 (HCLP) % of energy from protein/carbohydrate/fat.

Results: Significant interactions between dietary intervention and time on total energy expenditure (TEE) (P = 0.013), sleeping metabolic rate (SMR) (P = 0.040), and diet-induced thermogenesis (DIT) (P = 0.027) appeared from baseline to wk 12. TEE was maintained in the HPLC diet group, while it significantly decreased throughout the intervention period in the HCLP diet group (wk 1: P = 0.002; wk 12: P = 0.001). Energy balance was maintained in the HPLC diet group, and became positive in the HCLP diet group at wk 12 (P = 0.008). Protein balance varied directly according to the amount of protein in the diet, and diverged significantly between the diets (P = 0.001). Fullness ratings were significantly higher in the HPLC vs. the HCLP diet group at wk 1 (P = 0.034), but not at wk 12.

Conclusions: Maintenance of energy expenditure on HPLC vs. HCLP diets at a constant body weight may prevent development of a positive energy balance, despite transiently higher fullness. 

Full-text

Alex’s Notes: Our good friend protein needs no introduction. It seems as though there is an increasing interest in this delicious macronutrient, especially with the huge focus against obesity. High-protein diets have two critical things going for them. For one, they are incredibly satiating relative to carbohydrates and fats, and second, they preserve lean body mass during times of dieting. Both of these work together to help induce fat loss, maintain the lower body weight, and sustain energy expenditure via lean mass preservation.

But with so many people becoming obese, it is worth asking what effect protein has on weight gain. We already have some clues. Even before we know what is going on, low protein diets of pregnant and lactating mothers can potentially reduce offspring muscle mass and elevate myostatin gene expression. Once we start supplementing our breast milk with whole foods, the effects are still apparent. Using meat as a complimentary food instead of standard cereals and carbohydrate-dominated foodstuffs leads to significantly greater overall growth in height and weight in breastfed infants. Moreover, it was the protein intake (g/kg/day) that was a significant predictor of total growth and the added weight came from lean mass rather than fat mass. Finally, overfeeding resistance-trained individuals with protein (4.4g/kg/day) has shown to have no significant impact on any marker of body composition.

The current study will add to our understanding by evaluating the influence of protein intake on energy expenditure during weight-stable conditions. Unfortunately, the study somewhat takes things to the extreme by randomly allocating the participants to a high-protein, low-carbohydrate diet (HPLC; 30/35/35 total energy intake as protein/carbohydrate/fat) or a low-protein, high-carbohydrate diet (LPHC; 5/60/35). Thus, while the study will be hard to apply to moderate amounts of protein, the protocol will give insight into potential effects of not enough protein in the diet compared to more than enough. That said, the study participants are 31 men and women with BMI’s ranging between 19-26 kg/m2 and aged between 19-34 years who did not smoke or consume more than ten alcoholic drinks per week.

All the participants went through their allocated dietary interventions for 12 weeks, during which time they received detailed dietary guidelines based on individual daily energy requirements (Harris-Benedict formula). The dietary guidelines consisted of a variety of recipes for breakfasts, lunches, dinners and snacks, including the food items and the amounts that had to be consumed. In order to ensure that the subjects could meet the macronutrient ratios, the guidelines had included the consumption of supplement shakes twice per day in addition to the other food. The HPLC consumed whey protein while the LPHC consumed maltodextrin. Interim visits were performed at weeks 5 & 9 to monitor compliance, as well as urinary nitrogen measurements to estimate protein intake, but it must be noted that the diets were not controlled and although guidelines were provided, it was up to the participants to follow them.

The exception was during the data collection piece of the study, which occurred within a respiration chamber before the intervention, after one week (short-term), and after 12 weeks (long-term). The participants received energy-balanced diets corresponding to their diet group, with daily energy intake divided over three meals, 20% at breakfast and 40% at both lunch and dinner. Two days before and during the baseline measurement, all subjects were provided with an energy-balanced diet containing normal relative protein content (15/50/35% of energy from protein/carbohydrate/fat). The respiration chamber tightly controlled for everything from sleep time, to meal time, to meal type. It allowed for the estimation of total energy expenditure (TEE), sleeping metabolic rate (SMR), activity energy expenditure (AEE), and respiratory quotient (RQ). Appetite, hunger, satiety, fullness, and desire to eat were also completed every hour during daytime, and all blood samples were taken at 8am after a 13-hour overnight fast.

Compliance and Body Composition

As would be expected, the urinary nitrogen levels increased by 84% in the HPLC group but decreased by 42% in the LPHC group, confirming adherence to protein intakes above and below the baseline 15%, respectively. After 12 weeks, bodyweight remained unchanged in both groups, but fat mass slightly decreased (3%), and fat-free mass (FFM) slightly increased (1%) with the HPLC group, while small increases in fat mass (3%) and small decreases in FFM (1%) were observed in the HCLP diet group. None of these body composition changes reached statistical significance, but it is interesting to observe given that bodyweight was literally the exact same (on average) after the intervention period.

Energy expenditure and substrate oxidation

When looking to metabolic parameters,TEE, SMR, and DIT were maintained throughout the intervention period on the HPLC diet, but were reduced after just one week on the LPHC diet and continued to decline over the entire 12 weeks culminating with significant differences from both baseline and the HPLC group.AEE was stable throughout the intervention period in both diet groups. I summarized the significant changes from baseline in the table below (“--“ means not significant).

 

Week 1 change from baseline

Week 12 change from baseline

 

HPLC

HCLP

HPLC

HCLP

TEE

--

↓4.5%

--

↓6%

SMR

--

--

--

↓3.5%

DIT

--

--

--

↓27%

AEE

--

--

--

--

RQ

↓1%

↑2%

↓2.3%

↑2%

Protein Oxidation

↑86%

↓40%

↑86%

↓46%

Carbohydrate Oxidation

↓23%

↑14%

↓23%

↑5%

Fat Oxidation

--

--

--

--

Interestingly and somewhat intuitively, the SMR was positively correlated with the LBM of the subjects, and changed accordingly. The small insignificant changes in FFM likely accounted for the minor and insignificant increase in SMR in the HPLC group and vice-versa for the HCLP group. Moreover, the higher protein intake may have also prevented adaptive thermogenesis, which was observed as a decreased SMR in the HCLP group.

You’ll also notice that the HPLC group significantly increased their protein oxidation rate by 86% after just one week and maintained it throughout the intervention, where as it continued to decrease throughout the 12-weeks in the LPHC group. Carbohydrate oxidation rates followed a somewhat opposite pattern, and fat oxidation didn’t change in either group even though the RQ was slightly lower in the HPLC group and higher in the LPHC group.

In the end, subjects in the HPLC diet group were in energy balance during all measurements in the respiration chamber, but the HCLP group actually entered a state of energy excess by week 12 and this was nearly significant at week one as well (p=0.051). This excess is likely underscored by the reductions in SMR and DIT, which in turn may be caused by the reductions in FFM and low-protein diet, respectively.

Appetite and Other Metabolic Things

Hunger and desire to eat were not significantly different between the diet groups and did not change significantly over time. On the other hand, fullness and satiety were significantly increased in the HPLC group by week one and remained non-significantly higher by week 12, while the HCLP group demonstrated the opposite. The non-significance by week 12 may represent a habituation effect whereby one become accustomed to eating more protein and thereby doesn’t receive the same initial benefits as someone just making the change. In other words,if energy intake is pre-determined, coping with an initial higher fullness on a high-protein diet by lowering energy intake is not possible, and habituation in appetite enables sustaining a high-protein diet in energy balance.

Fasting glucose and insulin did not change throughout the intervention in either group, although a trend (p=0.068) for lower glucose concentrations at week 12 did appear in the HPLC diet group. β-hydroxybutyrate (BHB) concentrations showed a significant elevation in the HPLC group at both weeks 1 and 12, whereas it significantly decreased by week 12 in the LPHC diet.

Bottom line

It appears that a higher protein diet works to maintain energy expenditure in normal weight young adults. At least, compared to a ridiculously low protein diet. Not really much else to say that hasn’t been said. It would have been nice if the authors provided the average protein intake as g/day so as to compare it to the subjects’ bodyweight, but regardless it appears that if you have to choose between 5 and 30% of energy intake as protein, go with the 30%.

 
 

Network Affiliates

Internet-Radio.com
SHOUTcast.com
TrulyHuge.com
FitnessLinkPros.com
WorldFitness.org
CriticalBench.com
LiftForLife.com
LiveLongerLiveStronger.co.uk

Quick Links I

Our Location

SUPER HUMAN RADIO
2908 Brownsboro Rd
Suite 103
Louisville, KY 40206
(502) 690-2200

SHR Newsletter

Subscribe to our FREE newsletter
to receive the latest updates in your inbox!
SHR Newsletter