Ramadan fasting (RF) is mandatory for all healthy adult Muslims and is practiced by Muslims globally once a year. Changes in sleeping patterns and circadian rhythms accompany the dawn-to-sunset abstention from all food and drink. There are also changes in food intake and appetite, with an increasing desire for food reaching a peak by iftar time; there are variable changes in weight, with an average weight loss of around 1–2 kg reported in various studies, including meta-analyses. There is, therefore, no doubt that energy balance is altered during Ramadan fasting. In effect, there is gradual glycogen depletion during the day, followed by replenishment in the evening. As the Ramadan fasting day progresses, there is a gradual shift in fuel utilization from carbohydrate to fat. Whether and how different components of energy expenditure (EE) change during Ramadan is a question of interest and has important implications. There is much inter-individual variability in changes in various aspects of energy metabolism in the context of Ramadan fasting. The handful of studies on energy expenditure during Ramadan fasting seem to point to overall insignificant changes to resting metabolic rate (RMR) and total energy expenditure (TEE). However, activity energy expenditure (AEE) is altered in timing and duration and is, on average, reduced. Sleeping pattern, time, and quality change with a net overall, mostly modest reduction in duration. To date, no direct studies of the thermic effect of food (TEF) have been performed during Ramadan fasting. This review examines the existing evidence on energy balance in the context of Ramadan and will discuss the possible implications not just for Ramadan but beyond.