Intermittent fasting is increasing in popularity as a way to lose weight and assist in managing pre-diabetes, type 2 diabetes and type 1 diabetes. But what do we mean by intermittent fasting? Is it as good as, or better than, normal energy restriction and slow and steady weight loss? And is it safe and suitable for those with diabetes?

What is intermittent fasting?

The term intermittent fasting implies a reduced energy intake on an intermittent basis. Individuals may choose to follow such diets for religious reasons, for weight control or to assist with chronic health conditions such as diabetes. It is one of the methods of weight loss that has been associated with the diabetes remission studies.

 Some examples of intermittent fasting diets are described below:

• 16/8 method: Each day you fast for 16 hours and only eat during the remaining 8 hours. It is also called a time restricted diet.
• The 5:2 diet: In a week you eat normally for five days and on the other two days you eat no more than 500-600 kcal (2100-2500 KJ).
• Alternate day fasting: Three-four 24 hour fasts each week. You eat dinner only on days of the fast and lunch and dinner on the other days, with a focus on low carb meals.

How fasting works

Intermittent fasting results in less energy being consumed, which consequently reduces body fat and muscle mass or weight. Weight loss can improve insulin resistance and blood glucose levels similar to other energy restricted diets. However, there may be additional potential benefits that are currently being researched. These include cardiovascular metabolic changes that occur when ketosis or fat burning is induced during long fasting periods, changes to inflammatory markers, blood pressure, cholesterol levels, gut hormones, cognitive decline, and even the oxygen capacity of red blood cells.

Is it safe?

Intermittent fasting can be safely undertaken if you have diabetes; however, there are some considerations. Firstly, you should discuss with your doctor to determine if it is suitable for you. You may have other health conditions along with your diabetes that complicate matters. You may also need to make changes to the dose of diabetes, and other, medications. With respect to diabetes, it is important to reduce the risk of hypoglycaemia and dehydration in particular. If you are on medications that can cause hypoglycaemia, it is important to monitor your blood glucose levels more frequently even if the dose is reduced.

Other considerations

Hydration is important, and you may need to drink additional water to replace fluid that you would normally consume through food, to ensure adequate fluid intake each day. Blood pressure medication may also need to be reviewed.

Other considerations, especially when a diet is undertaken for longer periods, is making sure you get enough nutrition. Obtaining sufficient protein, vitamins and minerals remains an important aim of all diets.

Effect on other health conditions

The effect of intermittent fasting for those with other health conditions is unknown. This includes those with established coronary artery disease, especially those who have had a heart attack, stroke or TIA (transient ischaemic event). The effects are also unkown for those with unstable angina, heart failure, atrial fibrillation, most cancers, those who are immunosuppressed, have chronic obstructive airways disease, blood clots, and chronic kidney disease.

Pregnant and breastfeeding women, children, frail and older adults should not engage in intermittent fasting. Those with dementia or who have an eating disorder are best not to follow an intermittent fasting regimen.

Studies

Studies are limited to a time frame and whether individuals can sustain intermittent fasting long term is unclear. In the short term they appear to be well tolerated, easy to adjust to and without serious adverse events. Transient headaches can occur but adequate hydration can help. If you find these diets cause you to feel unwell, irritable, anxious or make it harder for you to cope with stress then perhaps it is not the right type of diet for you.

You should also consider how such diets will impact on those you live with, and your social life.  

Intermittent diets are one way to lose weight and can assist to reduce insulin resistance and improve blood glucose levels. With considerations, many people with diabetes can safely try intermittent fasting, although it won’t suit everyone.

By Helen d’Emden AdvAPD CDE Mphil