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

PMID: 31700709
Journal: Cureus
Published: 2019 Sep 8
Authors: 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.

## Population

- Adults with metabolic syndrome
- Sample size: 12
- Age: 40.9 +/- 20.2 years
- Sex: 4 men, 8 women
- Fitness level: Relatively sedentary
- Health status: Metabolic syndrome

## Methodology

- Randomized two-phase crossover dietary and exercise trial
- Two 4-week intervention phases separated by a 4-week washout
- Free-living diet intervention plus private supervised laboratory cycling sessions
- Randomized and controlled study design.

## Protocol

- CRPD plus cycling HIIT.
- Modality: Cycle ergometer.
- Work intervals: 60 seconds.
- Recovery: 60 seconds active recovery at 50 W.
- Sets or repetitions: 10 intervals.
- Intensity: ~90% HRmax.
- Session duration: 26 minutes.
- Frequency: 3 days/week.
- Program length: 4 weeks.
- Progression: None reported.
- CRPD with sedentary behavior.
- Program length: 4 weeks.

## Outcomes

### cardiometabolic markers
Status: improved
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

### inflammation
Status: improved
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%

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

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

### tolerability
Status: no clear change
All subjects tolerated and complied with the exercise protocol.

## Practical 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 And Adherence

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

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/31700709/) (pubmed)
- [DOI](https://doi.org/10.7759/cureus.5596) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6822889/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.