PMID 34993222

Research
All papers

Effects of a Very Low-Carbohydrate High-Fat Diet and High-Intensity Interval Training on Visceral Fat Deposition and Cardiorespiratory Fitness in Overfat Individuals: A Randomized Controlled Clinical Trial

Cipryan L, Dostal T, Litschmannova M, Hofmann P, Maffetone PB, Laursen PB

Question

What are the separate and combined effects of a very-low-carbohydrate high-fat diet and walking-based HIIT on visceral fat, body composition, and cardiorespiratory fitness in overfat adults?

Summary

In adults with overweight or obesity, a very-low-carbohydrate high-fat diet reduced visceral fat and other body-fat measures over 12 weeks, while HIIT improved exercise time but did not independently reduce visceral fat. Combining VLCHF with HIIT improved exercise capacity but did not add clear visceral-fat benefit beyond the diet condition.

Methodology

  • Ninety-one nonsmoking adults aged 20-59 years with BMI 25-40, low physical activity, no regular sports training, and without major metabolic, cardiopulmonary, renal, liver, cancer, psychiatric, pregnancy, or medication-related exclusions.
  • 91 participants.
  • Self-performed walking intervals.
  • Work intervals: 3 min high-intensity walking.
  • Recovery: 3 min low-intensity walking.
  • Intensity: High intervals RPE 18-19; low intervals RPE 9-11.
  • 31 min, 43 min, then 55 min including warm-up and cool-down as intervals progressed.
  • 3 sessions/week.
  • 12 weeks.
  • Randomized controlled four-arm parallel clinical trial
  • DXA visceral adipose tissue, Body mass, fat mass, trunk fat, waist and hip circumference, Lean mass, and Treadmill time to exhaustion were tracked.

Outcomes

Visceral fat

Visceral adipose tissue decreased significantly in VLCHF and VLCHF plus HIIT groups, but not in HIIT alone or control.

Mixed

Body composition

Body mass, total fat, trunk fat, waist, and hip measures decreased most clearly in the VLCHF groups; lean mass also decreased in VLCHF groups.

Mixed

Exercise capacity

Time to exhaustion improved in HIIT and VLCHF plus HIIT compared with diet-only and control conditions.

Improved

VO2peak

Relative VO2peak increased most in the VLCHF plus HIIT group, but absolute VO2peak and VT2 did not clearly change.

Mixed

Insights

  • Walking HIIT can improve treadmill exercise capacity in overfat adults, but this trial did not show HIIT alone reducing visceral fat.
  • Body-composition claims in this study are strongly influenced by the dietary intervention.
  • Longer 3 min intervals with RPE targets were used rather than short sprint intervals.

Limitations

  • Real-life adherence to diet and activity records was not fully controlled.
  • Groups were not fully balanced by sex, and the HIIT group had a slightly higher median age.
  • Menstrual cycle and menopause status were not considered.
  • Diet cointervention complicates attribution in combined arms.
  • HIIT was self-performed for most sessions.

Safety

  • The trial used extensive health exclusions. No adverse events were clearly reported in the the paper.