Despite substantial breakthroughs in pharmacological therapies for multiple sclerosis (MS) over the past two decades, lifestyle modification remains an important strategy in managing symptoms and potentially preventing disability for people with MS. There is growing evidence that certain dietary factors may influence MS incidence, symptoms and disease course. Obesity, which is closely linked to diet, has been shown to be a risk factor for the development and increased severity of MS. Although the precise mechanisms by which the above factors exert their effects on MS are unknown, it is important for physicians to consider how these factors can influence the management of patients with MS. For example, sleep interventions and regular exercise may help with the common symptoms of MS, such as fatigue, cognitive dysfunction and mood disorders. Other important interventions include avoidance of tobacco smoke and adequate vitamin D intake. This review summarizes existing knowledge regarding the abovementioned factors with respect to MS incidence and severity.