Cardiorespiratory fitness improved with exercise and was not impaired by the VLCHF diet
A very-low carbohydrate high-fat (VLCHF) diet, either in isolation or in combination with high-intensity interval training (HIIT), has been demonstrated to induce a significant reduction in visceral adipose tissue (belly fat) mass and body composition variables. HIIT alone did not cause such effects.
A new study, published in the journal Frontiers in Nutrition, found that the VLCHF diet intervention, less than 50 grams per day, had a greater effect on improving body composition than exercise alone, and that a VLCHF diet can be an effective strategy for reducing excess body fat. The incorporated HIIT program had no additional effects on reducing body composition variables, and in particular, belly fat. HIIT alone, and when combined with VLCHF, did improve cardiorespiratory fitness.
This randomized controlled parallel-group study examined the effects of a VLCHF diet and a HIIT program over 12 weeks on abdominal fat and cardiorespiratory fitness level in overfat individuals (defined as having excess body fat that impairs health and fitness). The significant belly fat decrease in the VLCHF group was revealed after only four weeks and continued after 12 weeks. The absolute belly fat mass (g) was reduced by 23.2 percent in the VLCHF group, and by 17.6 percent in the VLCHF+HIIT group.
HIIT alone did not cause a substantial belly fat decrease, nor did it produce any significant changes in other body composition variables compared to the control group. When HIIT was combined with the VLCHF diet, no extra belly fat changes were revealed either. HIIT alone, and in combination with the VLCHF diet, did substantially improve exercise performance.
The study included 91 men and women aged 20-59 randomly allocated to the HIIT, VLCHF, VLCHF+HIIT, or control groups for 12 weeks. Body composition and cardiorespiratory fitness were analyzed before the experimental period, and at four, eight, and 12 weeks. Dual-energy X-ray absorptiometry (DXA) and anthropological measures (waist-to-hip, waist-to-height) demonstrated the overweight/obese/overfat conditions. A graded exercise test to volitional exhaustion on a treadmill was used for the cardiorespiratory fitness and exercise performance assessments.
The new Frontiers in Nutrition study is titled “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” by Lukas Cipryan, Tomas Dostal, Martina Litschmannova, Peter Hofmann, Philip B. Maffetone, and Paul B. Laursen (doi: 10.3389/fnut.2021.785694).