Strength training will result in more muscle mass when combined with a protein-rich diet. Nothing new here, but that strength training combined with a protein-rich diet is healthier might be news to you. Researchers at Pusan National University in South Korea reach this conclusion in a small human study that they published in the Journal of Diabetes Investigation.
The Koreans got 18 males in their twenties, none of whom had previously done weight training, to do strength training for a period of 12 weeks. The men did working sets with 60-80 percent of the weight with which they could just manage 1 rep.
Half of the subjects ate a more or less ‘normal’ diet during the experiment. The energy in their diet consisted of 60 percent energy derived from carbohydrates, 15 percent from protein and the remaining 25 percent from fat. [norm.-prot.]
The other half of the men ate a protein-rich diet. In that diet the energy was derived for 55 percent from carbohydrates, 30 percent from protein and 15 percent from fat. [high-prot.]
Both groups consumed the same amount of kilocalories.
After the training period the researchers discovered that the men who had followed the high-protein diet had built up more lean body mass. This was not the case for the men who had consumed a normal amount of protein in their diet.
The body fat percentage had declined in both groups, but the decrease was bigger in the men who had eaten more protein.
The Koreans detected no dramatic effects of the combination of strength training and a high-protein diet on IGF-1, cortisol and testosterone levels. What they did observe was that there was considerably more growth hormone circulating in the blood of the subjects in the high-protein group than in the subjects that had eaten less protein.
The HOMA-IR – a measure of insulin resistance – decreased in the men who had consumed a lot of protein. This meant that their cells became more sensitive to insulin, which is a positive sign.
Moreover, the cholesterol balance of the men who had eaten the high-protein diet improved. Their amount of ‘good cholesterol’ HDL increased.
“In conclusion, these findings suggest that there are hormonal interactions to ameliorate body composition, metabolic profiles, and energy metabolism after a long term higher protein diet and resistance exercise”, the researchers summarise. “However, replication studies with various types of resistance exercise programs and high protein diet are required in order to confirm the results of the present study for current practice in the field.”
Interactive effects of an isocaloric high-protein diet and resistance exercise on body composition, ghrelin, and metabolic and hormonal parameters in untrained young men: A randomized clinical trial.
The interactive effects of resistance training and dietary protein on hormonal responses in adults are not clear and remain controversial. We tested the effect of an isocaloric high-protein diet on body composition, ghrelin, and metabolic and hormonal parameters during a 12-week resistance training program in untrained healthy young men.
MATERIAL AND METHODS:
We randomized 18 healthy young men to a standard diet (ST group) or an isocaloric high protein diet (HP group). Both groups participated in a 12-week resistance exercise program. We measured body composition, lipid profile, homeostatic model assessment of insulin resistance (HOMA-IR) indices, total ghrelin, and exercise-related hormones at baseline and 12 weeks.
In the HP group, lean body mass (LBM), total ghrelin, growth hormone, testosterone and cortisol levels showed an increase, whereas body fat percentage and HOMA-IR showed a decrease at 12 weeks, compared with baseline (P ≤ 0.05). In the ST group, no changes in these parameters were observed during the 12-week period. During the 12-week period, significant differences in the pattern of change of LBM (P = 0.032), total ghrelin (P = 0.037), HOMA-IR (P = 0.040) and high-density lipoprotein cholesterol (P = 0.011) over time were observed between the groups.
The findings of the present study suggest that an isocaloric high-protein diet can ameliorate body composition, metabolic profiles and energy metabolism during a 12-week scheduled resistance training program in untrained healthy young men. This trial was registered with ClinicalTrials.gov (no. NCT01714700).
PMID: 24843767 PMCID: PMC4023590 DOI: 10.1111/jdi.12148