The pros and cons of intermittent fasting revealed

Fans are raving about this new diet trend - but does it really work? Photo / Getty Images

Fasting is one of the most popular new areas of dieting, with fans raving about the weight loss, mood boost and improvement to skin and energy levels.

With a range of different regimes from low-calorie days to eating just one meal over 24 hours, there is growing evidence to show that our body does benefit from regular fasting.

My nutrition clients often ask me about fasting as cost and time-effective routines are very much on trend.

While the published research shows that there can be marked improvements in blood-glucose, cholesterol, blood pressure and insulin levels, weight loss is a lesser, secondary benefit.

This is not to say that you will not lose weight if you incorporate fasting into your regular food regimen, rather weight loss tends to be a secondary outcome for individuals battling inflammatory conditions such as heart disease, insulin resistance and fatty liver.

So if you know your body could benefit from a change in routine, here's my guide to choosing the right type of fasting for you.

The 5:2

Intermittent fasting has gained significant attention off the back of the work of British scientist Dr Michael Mosley who authored the 5:2 Diet. The 5:2 plan incorporates two non-consecutive days of very low-calorie eating, followed by five days of regular, non-restrictive eating. It is shown that blood pressure, cholesterol and insulin levels are improved when the body has limited exposure to calories for brief periods.

While the 5:2 can be extremely effective it is not the easiest diet to follow. With females required to consume just 500 calories and males 600 calories on low-calorie days, this means that on two days of the week you will not be eating very much. For example, 500-600 calories spread over two meals equates to one poached egg with 1 cup of vegetables, a piccolo coffee in one meal and just 80-100g fish and vegetables or salad in the other.

For non-eaters, such as busy businesspeople or shift workers, this may not seem that extreme but for the average person, who tends to eat several times a day, such a shift in eating habits may not prove that easy, particularly in social situations.

Pros: Only need to diet strictly two days each week.

Cons: Severe calorie restriction and associated hunger, even for just two days is tough.

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A post shared by Susie Burrell (@susiediet) on Sep 16, 2020 at 11:56pm PDT

The 16:8

Followers consume all their calories within an eight-hour time window and fast for the remaining 16 hours — no snacking or grazing.

This limits food intake to one or two meals each day.

Here, by eating fewer meals and no snacks, calorie intake tends to be automatically reduced. As such, there is no need to count calories or be choosy with the foods you eat within your eight hours, and rather you are encouraged to eat one to two satisfying meals. An example of a 16:8 day is a larger breakfast of eggs, toast, coffee and fruit late morning, and a second meal of fish, sweet potato and vegetables 6-7 hours later.

The 16:8 suggests that having an extended period of time without food overnight (14-16 hours) helps to regulate blood pressure, blood cholesterol and some of the hormones that control fat metabolism a lot more effectively, ultimately supporting the health of the body's cells and weight control.

Pros: It is relatively easy to follow and involves no calorie counting.

Cons: There is less focus on diet quality, so weight loss may be slower depending on food choices made.

5:2

Sample fasting day:

Boiled egg, piccolo coffee

Tuna salad

100g white fish, 2 cup green veg stir-fried with soy sauce

How much weight can you lose: ½kg to 1kg a week.

My tip: Suits those with sedentary lifestyles and low energy demands.

16:8

Sample fasting day:

Two eggs, two slices wholegrain toast, tomatoes, mushrooms, latte

Handful of nuts

Salmon fillet, roasted sweet potato, broccoli, green beans. Tub of Greek yoghurt.

How much weight can you lose: 1-2kg a month

My tip: Focus on nutritious foods for each of your two meals to ensure you are getting what you need to support weight loss.