Photo: Display of healthy food

Fasting-mimicking diets - what’s the evidence?

Fasting-mimicking diets (FMDs) have hit the headlines with new research discussing their potential for people with MS. But what did the study show? We take a look behind the headlines.

An FMD involves a period of ‘fasting’ over three to seven days, during which calorie intake is reduced by 50-90%. There are many variations of an FMD, which can differ in the number of days of fasting and the number of cycles.

Researchers tested three cycles of an FMD on mice, where food intake was restricted for three out of every seven days. They then carried out a pilot study involving people with MS, which involved a single fast lasting seven days.

Cutting back on the cheese

Researchers found three cycles of an FMD reduced the severity of a mouse model of MS (known as EAE) compared to mice eating a control diet.

Results suggest mice on the FMD had increased levels of a hormone called corticosterone, which is involved in the stress response in mice.

The diet reduced the number of immune cells attacking myelin, and may also help to promote myelin repair.

Testing the benefits for people with MS

Researchers went on to test the potential of a modified FMD for people with relapsing MS in a small pilot study. They compared people doing a single, seven day fast followed by six months on a Mediterranean diet to a group of people continuing to eat their normal diet.

Researchers reported people following a modified FMD as part of the study experienced a mild improvement in their Extended Disability Status Scale (EDSS) scores. They also reported an improved quality of life compared to those eating their normal diet.

As the trial involved relatively few people and only lasted six months, it is difficult to draw conclusions about the long-term safety and effectiveness of this type of diet for people with MS. It is also not easy to assess whether the effects seen were due to the single fast or whether the Mediterranean diet had benefits compared to the control diet.

To address these issues, researchers are planning larger controlled studies.

What role does diet play in managing MS?

Diet is an emerging area of MS research many people are interested in. Some people with MS say following a specific diet has made a difference to how they feel. Other people haven’t noticed any specific benefits and overall there is limited evidence to suggest one particular diet is effective in managing MS.

Designing studies to test how effective a diet in managing MS is a tricky business, as the studies have to run over a long period of time and be tightly controlled to ensure any effects seen are due to the diet in question. On a practical level, it’s also difficult to ensure everyone taking part in a study eats the same thing over the course of several months or years.

Ultimately, diet and nutrition is a matter of personal choice.