Time-restricted eating plus high-intensity exercise lower visceral fat for women
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Women who combine time-restricted eating with high-intensity interval training have greater reductions in visceral fat area than those who perform only one of the interventions, according to a study published in Cell Metabolism.
“Time-restricted eating offers a relatively simple method for changing dietary habits by only focusing on meal timing and usually induces a spontaneous reduction in energy intake without deliberate effort,” Kamilla La Haganes, a PhD student, and Trine Moholdt, PhD, a research scientist in the department of circulation and medical imaging, faculty of medicine and health sciences at Norwegian University of Science and Technology in Trondheim, Norway, told Healio. “High-intensity interval training offers a relatively time-efficient and effective exercise strategy for inducing greater improvements in cardiorespiratory fitness compared with moderate-intensity exercise. Our findings of improved body composition, metabolic health and high adherence rates suggest that women at high risk for cardiometabolic disorders can improve their health with a combined time-restricted eating and high-intensity interval training program, and that it is safe and feasible for this population.”
La Haganes, Moholdt and colleagues conducted a randomized controlled trial in which 131 women with overweight or obesity were randomly assigned to a time-restricted eating intervention with eating restricted to a window of 10 hours or less each day, a high-intensity interval training intervention with three supervised treadmill exercise sessions per week, an intervention combining time-restricted eating and high-intensity interval training and a control group with no intervention. The trial duration was 7 weeks. Participants completed the trial between August 2019 and January 2021. Fasting blood samples, blood pressure and resting heart rate were collected at baseline and at the end of 7 weeks. Participants also performed a cardiorespiratory fitness test to measure peak oxygen uptake and underwent a 2-hour oral glucose tolerance test at baseline and the end of the trial. The study’s primary outcome was the difference in total glucose area under the curve between the four groups.
Combined intervention linked to largest visceral fat loss
Total glucose AUC was similar for all interventions. Women who performed the combined intervention had a slight reduction in HbA1c from 34.6 mmol/mol to 33.9 mmol/mol from baseline to 7 weeks (P = .008). Women who performed high-intensity interval training or the combined intervention had slight improvements in peak glucose. The combined intervention group also had improvements in 30-minute insulin concentration (77.4 µIU/mL vs. 71.1 µIU/mL; P = .012) and nocturnal glucose (4.5 mmol/L vs. 4.4 mmol/L; P = .024) from baseline to 7 weeks, while the time-restricted eating group had a reduction in 24-hour glucose (5.1 mmol/L vs. 4.9 mmol/L; P = .016).
“We were surprised that there was little to no change in our primary outcome, glucose area under the curve during an oral glucose tolerance test, or in insulin levels,” La Haganes and Moholdt said. “However, we believe the reason for the lack of substantial change in these parameters were the normoglycemic baseline status of the participants in this study.”
All three intervention groups had greater decreases in body weight, fat mass and visceral fat from baseline to 7 weeks than the control group, and women in the combined intervention group had greater reductions in all three body composition categories compared with the time-restricted eating intervention and the high-intensity interval training intervention.
The high-intensity interval training and combined intervention groups had a 9% improvement in peak oxygen uptake from baseline to 7 weeks, whereas no change was observed with time-restricted eating. None of the interventions were associated with a difference in blood lipids, appetite hormones and vital signs.
Women in the time-restricted eating and combined interventions had a reduction in estimate daily energy intake of about 840 kJ during the last 2 weeks of the trial compared with baseline. Hunger and desire to eat increased in both groups during the first week of the trial compared with the control group, but there was no difference between the groups by the end of the intervention.
Research on men, follow-up study to come
La Haganes and Moholdt said more research is underway to examine the effects of time-restricted eating combined with high-intensity interval training in men. Additionally, women who participated in the trial are being invited to participate in another study where they will answer questions about adherence and perceptions of the interventions and have follow-up lab tests performed.
“This 2-year follow-up study will give us insight to how time-restricted eating and high-intensity interval training might be maintained after a familiarization period provided through a study setting, and whether any health benefits initially induced by the interventions are maintained over the long term,” La Haganes and Moholdt said.
For more information:
Kamilla La Haganes can be reached at kamilla.l.haganes@ntnu.no.
Trine Moholdt, PhD, can be reached at trine.moholdt@ntnu.no.
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