Intermittent Fasting

Intermittent fasting is an eating pattern that cycles between periods of eating and periods of fasting. Rather than telling you which foods to eat, it focuses on when you eat them. It has become popular as a weight management tool, but it is not the right approach for everyone, and the quality of what you eat in your eating window still matters.

What is intermittent fasting?

The most common approaches involve fasting for around 16 hours each day, or fasting for 24 hours once or twice a week. Fasting itself is not new: throughout human history people have gone without food for periods of time, and fasting is part of many religious and spiritual traditions. For many clients in the Gulf, for example, Ramadan is already a familiar fasting experience, and we plan nutrition around it when needed.

Popular methods

• 16/8 (time-restricted eating): you eat within an 8-hour window, for example 12:00 to 20:00, and fast for the remaining 16 hours.
• Eat-stop-eat: a 24-hour fast once or twice a week, for example from dinner one day to dinner the next.
• 5:2: on two non-consecutive days of the week energy intake is kept very low, and on the other five days you eat normally.

Many people find the 16/8 method the simplest and easiest to keep up, which is why it is also the most widely used.

What happens in the body?

During a fast the body adjusts its hormone levels to make stored fat easier to use. Insulin levels fall and insulin sensitivity may improve, growth hormone levels rise, and cells start repair processes such as autophagy, in which old and damaged proteins are broken down and recycled. These changes are the reason intermittent fasting is being researched for metabolic health.

Intermittent fasting and weight management

Weight loss is the most common reason people try intermittent fasting. A shorter eating window often leads to eating less without counting calories. Studies have reported modest weight loss and reductions in waist circumference over several weeks to months, and some research suggests less muscle loss than with continuous calorie restriction. However, the main driver is still a lower overall energy intake: if you eat large amounts during your eating window, you are unlikely to lose weight. Intermittent fasting may also improve fasting blood sugar and insulin levels in some people, but anyone with diabetes needs their doctor's input before trying it. Results vary from person to person.

For a broader, personalised approach, see weight loss and weight management.

Women and intermittent fasting

Some evidence suggests intermittent fasting may not suit women as well as men. There are reports of women whose periods stopped after starting fasting and returned when they went back to their usual eating pattern. Women should take care, and stop if they notice problems such as missed periods. Women trying to conceive, or who are pregnant or breastfeeding, should not follow intermittent fasting; see preconception nutrition and pregnancy nutrition instead.

Side effects and who should avoid it

Hunger is the main side effect, and you may feel weak or tired at first while your body adjusts. Talk to your doctor before trying intermittent fasting if you:

• have diabetes or problems with blood sugar regulation,
• have low blood pressure,
• take regular medication, including weight-loss medication prescribed by your doctor,
• are underweight,
• have a history of eating disorders,
• are trying to conceive, have a history of missed periods, or are pregnant or breastfeeding.

Getting started

Many people already fast for long periods without noticing: if you have dinner, sleep late and skip breakfast, you may have fasted for more than 16 hours. If you want to try it, 16/8 is usually the gentlest starting point, and the eating window should contain balanced meals with enough protein, vegetables, whole grains and fluids. Intermittent fasting is only one of many lifestyle strategies. Eating well, moving regularly and sleeping enough matter more, and there is no single approach that suits everyone. The right plan is the one you can keep up comfortably and safely.

Frequently asked questions

Can I drink during the fasting period?

Water, plain tea and black coffee are usually allowed. Drinks with sugar, milk or calories break the fast.

Does intermittent fasting slow down metabolism?

Short fasts are not thought to slow metabolism, but very long or frequent fasts and very low intake can affect energy, muscle and wellbeing, which is why the plan should be individual.

Can a dietitian help me fast online from abroad?

Yes. In online consultations held in English, we decide whether fasting suits you, choose an eating window that fits your work hours and time zone, and plan balanced meals.

If you would like to know whether intermittent fasting is a good fit for you, get in touch or message me on WhatsApp.