PMID 31700709

Research
All papers

Carbohydrate-restricted Diet and High-intensity Interval Training Exercise Improve Cardio-metabolic and Inflammatory Profiles in Metabolic Syndrome: A Randomized Crossover Trial

Gyorkos A, Baker MH, Miutz LN, Lown DA, Jones MA, Houghton-Rahrig LD

Question

Does adding 4 weeks of supervised cycling HIIT to a carbohydrate-restricted Paleolithic diet improve body composition, cardiovascular, inflammatory, and metabolic markers in adults with metabolic syndrome compared with the same diet and sedentary behavior?

Summary

In 12 adults with metabolic syndrome, a 4-week carbohydrate-restricted Paleolithic diet improved weight, waist, glucose, lipids, insulin resistance, inflammation, blood pressure, and VO2max. Adding supervised cycling HIIT to the diet produced larger improvements for several markers, but the design makes this diet-plus-exercise evidence rather than HIIT-only evidence.

Methodology

  • Adults with metabolic syndrome
  • 12 participants.
  • Cycle ergometer.
  • Work intervals: 60 seconds.
  • Recovery: 60 seconds active recovery at 50 W.
  • Intensity: ~90% HRmax.
  • 26 minutes.
  • 3 days/week.
  • 4 weeks.
  • Randomized two-phase crossover dietary and exercise trial
  • Metabolic syndrome markers, Insulin resistance, Inflammation, and VO2max were tracked.

Outcomes

cardiometabolic markers

Both phases improved MetS risk factors, with several larger improvements during diet plus HIIT.

Waist -15%/-18%, glucose -20%/-27%, TG -47%/-52%, HDL +22%/+36% for diet-only/diet-plus-HIIT

Improved

inflammation

Both phases reduced hsCRP, TNF-alpha, IL-6, and ICAM-1 versus baseline.

hsCRP -32%/-36%, TNF-alpha -35%/-41%, IL-6 -29%/-40%, ICAM-1 -19%/-23%

Improved

VO2max

VO2max increased in both phases, with a larger percentage increase during diet plus HIIT.

+22% CRPD-Sed and +29% CRPD-Ex

Improved

tolerability

All subjects tolerated and complied with the exercise protocol.

No clear change

Insights

  • A 10 x 1-minute cycling HIIT block is a concrete template for metabolic-health programming under supervision.
  • The strongest outcome story is combined diet plus HIIT, so claims should not isolate the workout unless scoped carefully.
  • For higher-risk users, screening and a monitored start are more important than maximizing intensity.

Limitations

  • N=12
  • Short 4-week intervention periods
  • Diet co-intervention dominates translation
  • No long-term maintenance data
  • Limited safety detail

Safety

  • No adverse events were reported in the reviewed text.
  • Clinical exclusions were broad despite enrolling metabolic syndrome participants.