A recent study published in Nutrients explores how combining high-intensity interval training (HIIT) with either intermittent fasting (IF) or a low-calorie diet (LCD) enhances metabolic health in postmenopausal women.
The Role of Nutrition and Exercise in Managing Menopause Symptoms
Menopause triggers several physiological changes, including increased visceral fat accumulation and reduced muscle mass. These changes, primarily caused by declining estrogen levels, contribute to systemic inflammation, insulin resistance, and a higher risk of metabolic disorders.
To address these challenges, experts recommend a combination of nutritional strategies and physical activity. Intermittent fasting (IF) is one such dietary approach, involving alternating eating periods with prolonged fasting. A common IF method, the 16:8 plan, consists of fasting for 16 hours and eating within an 8-hour window.
IF influences appetite-related hormones, including orexin-A (OX-A), a hypothalamic hormone responsible for energy balance and eating behavior regulation. During fasting, orexin neurons become active, stimulating hunger-related hormones such as neuropeptide Y (NPY) and agouti-related peptide (AgRP). These hormones enhance sympathetic activity, promoting thermogenesis and fat breakdown, which help restore cellular energy under fasting conditions.
Research suggests that IF improves metabolic flexibility, allowing cells to switch between glucose and fat as energy sources. This process supports fat oxidation, enhances insulin sensitivity, and reduces inflammation. Key biological mechanisms involved include the activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK), autophagy stimulation, mitochondrial support, and antioxidant effects.
HIIT complements these metabolic benefits by inducing acute metabolic stress while boosting cardiorespiratory fitness. The mechanisms through which HIIT improves health overlap with those of IF. Notably, the combination of HIIT and IF leads to higher OX-A levels compared to either approach alone. OX-A also activates brain reward pathways, increasing motivation for physical activity while enhancing fat metabolism and metabolic flexibility.
Study Insights
The study involved 30 postmenopausal women, averaging 57.5 years of age, who followed either a low-calorie diet (LCD) or intermittent fasting (IF) alongside HIIT for eight weeks. At the start of the study, the LCD group demonstrated better endurance and flexibility, whereas the IF group exhibited greater exercise tolerance and aerobic capacity.
Both LCD and IF, when paired with HIIT, resulted in metabolic enhancements, improved physical performance, and neurohormonal regulation. LCD primarily reduced fat mass through caloric restriction, while IF facilitated metabolic switching and fat oxidation.
Participants in the IF-HIIT group displayed notable improvements in flexibility, endurance, and maximum oxygen uptake (VO2) by the end of the study. Their mean heart rates and overall stamina exceeded those observed in the LCD-HIIT group.
Throughout the intervention period, OX-A levels significantly increased, with the IF group experiencing the most pronounced changes. At baseline, the IF group had higher OX-A levels than the LCD group. After eight weeks, OX-A levels in the IF-HIIT group had tripled, registering more than twice the increase seen in the LCD-HIIT group.
While LCD effectively reduced fat mass and improved insulin sensitivity, IF played a stronger role in enhancing metabolic flexibility and fat metabolism.
