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Does whey protein supplementation during resistance exercise have additional benefits for decreasing hepatic fat content?

  • 2023-05-27
  • Journal of the International Society of Sports Nutrition 20(1)
    • Chae-Been Kim
    • Hyoung-Su Park
    • Hye-Jin Kim
    • Hong-Soo Kim
    • Jung-Jun Park

Study Design

Type
Randomized Controlled Trial (RCT)
Sample size
n = 34
Population
34 sedentary males
Methods
Randomized assignment, 4 weeks of resistance exercise and diet control with 60 g/day whey protein supplement or isocaloric placebo
Blinding
Double-blind
Duration
4 weeks
Funding
Unclear

Background

Exercise and diet have positive effects on hepatic fat reduction, and protein supplementation is known to lower hepatic fat accumulation. However, the effect of a combination of exercise and whey protein supplementation (WPS) on hepatic fat content (HFC) is unknown.

Methods

We investigated the effect of WPS on HFC during resistance exercise and diet control intervention for four weeks. A total of 34 sedentary males participated and were randomly assigned to two groups: a protein supplement group (PSG, n = 18) and a control group (CG, n = 16). The PSG took 60 g of WPS per day, and the CG took 60 g of an isocaloric placebo per day. All participants were fed a calorie-controlled diet throughout the study period, with their daily caloric intake determined by their resting metabolic rate and physical activity level. Both groups performed resistance exercises supervised by experts at 60-70% of their maximum efforts for 60 min/day, 6 days/week for 4 weeks. HFC was assessed using the controlled attenuation parameter (CAP) after an 8 h fast, at pre-, mid-, and post-intervention. Liver enzymes and lipid profile were also analyzed after an 8 h fast and pre- and post-intervention.

Results

The CAP was significantly reduced after 4 weeks of intervention in both groups (PSG, p < .001; CG, p = .002). However, there was no significant interaction between the group and changes in CAP. Interestingly, when comparing the pre- and mid-tests, both groups also had significantly reduced CAP (PSG, p = .027; CG, p = .028), but there was a significant difference in the amount of change in CAP between the two groups (PSG, -47.2 ± 25.4 dB/m; CG, -19.5 ± 15.1 dB/m; p = .042). For liver enzymes, there was a significant interaction between the two groups and a change in aspartate transaminase (AST) (p = .038). However, alanine aminotransferase (ALT) levels were significantly decreased only in the PSG group (p = .002). In lipids, both groups showed significantly decreased total cholesterol (p < .001) and low-density lipoprotein cholesterol (p < .001) after the intervention.

Conclusion

Our data showed that WPS may not enhance the overall effects of resistance exercise on HFC and lipid profiles. However, in part, WPS may have a beneficial effect on liver enzymatic changes and rapid response to resistance exercise-induced HFC reduction.

Research Insights

  • Whey Protein→Reduced Alanine Aminotransferase Level

    alanine aminotransferase (ALT) levels were significantly decreased only in the PSG group (p = .002).

    Effect
    Beneficial
    Effect size
    Moderate
    Dose
    60 g/day
  • Whey Protein→Reduced Aspartate Transaminase Level

    For liver enzymes, there was a significant interaction between the two groups and a change in aspartate transaminase (AST) (p = .038).

    Effect
    Beneficial
    Effect size
    Moderate
    Dose
    60 g/day
  • Whey Protein→Reduced Blood Cholesterol

    In lipids, both groups showed significantly decreased total cholesterol (p < .001)... However, there was no significant interaction between the group and changes...

    Effect
    Neutral
    Effect size
    Small
    Dose
    60 g/day
  • Whey Protein→Reduced Hepatic Fat Content

    When comparing the pre- and mid-tests, both groups also had significantly reduced CAP (PSG, p = .027; CG, p = .028), but there was a significant difference in the amount of change in CAP between the two groups (PSG, -47.2 ± 25.4 dB/m; CG, -19.5 ± 15.1 dB/m; p = .042).

    Effect
    Beneficial
    Effect size
    Large
    Dose
    60 g/day
  • Whey Protein→Reduced Low-Density Lipoprotein Level

    low-density lipoprotein cholesterol (p < .001) after the intervention... However, there was no significant interaction between the group and changes...

    Effect
    Neutral
    Effect size
    Small
    Dose
    60 g/day
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