The Challenge of Maintaining Metabolic Health During a Global Pandemic

Abstract

The ongoing global pandemic brought on by the spread of the novel coronavirus SARS-CoV-2 is having profound effects on human health and well-being. With no viable vaccine presently available and the virus being rapidly transmitted, governments and national health authorities have acted swiftly, recommending 'lockdown' policies and/or various levels of social restriction/isolation to attenuate the rate of infection. An immediate consequence of these strategies is reduced exposure to daylight, which can result in marked changes in patterns of daily living such as the timing of meals, and sleep. These disruptions to circadian biology have severe cardiometabolic health consequences for susceptible individuals. We discuss the consequences of reductions in patterns of daily physical activity and the resulting energy imbalance induced by periods of isolation, along with several home-based strategies to maintain cardiometabolic health in the forthcoming months.

Fig. 1

The cyclical pattern of disruptions to metabolic homeostasis during prolonged periods of COVID-19 induced isolation. A lack, or loss of physical activity, increased sitting time and changes in dietary habits and sleep lead to several physiological and psychobiological outcomes directly impacting on metabolic homeostasis. Decreased rates of skeletal muscle protein synthesis, insulin resistance and impaired immune defence have a rapid onset during periods of inactivity and are exacerbated by disruptions to sleep quality and quantity. Insulin resistance and subsequent dysregulation of glucose metabolism predispose to weight gain and increased fat mass, creating a cycle of cumulative causation in which appetite is dysregulated as the cycle continues through prolonged inactivity. External stressors and loss of sleep (quality) created by self-isolation or ‘lockdown’ scenarios can lead to alterations in food choice, timing and quantity. Self-isolation also includes reduced outdoor access and the removal or alteration of exposure to external zeitgebers such as sunlight, with flow-on effects to behaviour, sleep and metabolism

Fig. 2

Exercise and nutrition strategies during COVID-19 isolation. A fundamental concern induced by isolation is a substantial reduction in energy expenditure. Implementing practical exercise and nutrition strategies can assist in maintaining metabolic health. a High-intensity interval exercise (HIT) involves short (30 s–4 min) repeated (4–10 bouts) of intense activity interspersed with 1–3 min of low- to moderate-intensity exercise or rest, and should be undertaken 3–5 times per week for 30 min. HIT rapidly induces increases in cardiorespiratory fitness as well as adaptations in skeletal muscle that assist in glycemic control. Depending on the availability of equipment, exercise prescription should be tailored to align with current/habitual levels of activity with the overall aim of reducing sedentary time (time spent sitting). “Exercise snacking” involves breaking up an exercise session into several shorter bouts spread throughout the day, and is also an effective strategy to enhance cardiorespiratory fitness compared with a single bout of the same duration. b Chrono-nutrition is the timing of food administration in coordination with the body’s daily rhythms, and reflects the basic idea that, in addition to the amount and content of food, the timing of meals is also critical for metabolic health. During periods of isolation, time-restricted eating (TRE), in which the daily “eating window” could be reduced from 12–14 h to 8–10 h, may help to reduce total energy intake, curtail discretionary food intake (i.e. alcohol, confectionery) in the evening, and improve overall dietary quality. c Consideration should be given to the timing and distribution of protein intake throughout a day to maximally stimulate rates of skeletal muscle protein synthesis. See text for details

Fig. 3

Summary of practical sleep strategies during isolation. The goal is to optimise sleep quality, duration and consistency. A regular daily sleep schedule, avoiding unnecessary naps (unless sleep deprived), exposure to sunlight in the morning, avoiding bright lights (including electronic devices) in the evening, and following natural sleep preference will help to achieve this goal