At the start of every new year I like to crystal ball the next twelve months to give you some insight into what diet trends will be popular in the coming year. At the start of 2018 my article focused on a diet call the Whole 30. This diet made some pretty big claims including reset your nutrition and rid you of unhealthy cravings and habits, restore a healthy metabolism, heal your digestive tract and balance your immune system. Well, it turns out I was wrong, thank goodness, about the Whole 30 diet as it is nowhere as popular in Australia as in the United States.
In 2019 we are going to see the keto diet gain more popularity but the new kid on the block is intermittent fasting. Intermittent fasting typically involves periods of restricted energy intake or fasting interspersed with ad libitum energy intake. Now, this isn’t exactly a diet but more of a structured eating pattern which includes following a structure diet.
The first person to really promote the benefits of intermittent fasting was Dr Michael Mosley who released the book The 5:2 Diet. This diet involves consuming your normal food intake for five days a week and on two days a week your food intake is reduced to between 500 – 600 calories, that’s around a quarter of the calories which most people need. As with any diet, the 5:2 diet book has a structured meal plan for all days which help control total energy intake and given you are consuming 1000 – 1500 calories less on two days a week, it’s no surprise people lose weight following this style of eating.
Like any good fad diet author, as the sales of The 5:2 Diet started to wane, Dr Michael Mosley has now released the Blood Sugar Diet Fast 800. Reacting to the popularity of the keto diet and the increasing variety of intermittent fasting diets hitting social media, the Blood Sugar Diet Fast 800 diet involves eating 800 calories and day consuming a Mediterranean style diet but shuns the carbs to force the body into ketosis. The diet has three stages. Stage one is simply eating 800 calories a day, this can last up to eight weeks. Stage two involves having 800 calories two days a week with a fourteen hour overnight fast with normal intake for the five other days. Stage three is maintenance following a Mediterranean diet with periods of intermittent fasting.
Now, there are a huge range of intermittent fasting methods than can be followed which includes 16/8 Method, Eat-Stop-Eat (24-hour fast one or two times a week), Alternate-Day Fasting, The Warrior Diet (fast during the day, eat a huge meal at night) and Spontaneous Meal Skipping. All of these diets involve some degree of fasting over a 24-hour period.
The most popular method is the 16/8 Diet which involves fasting for sixteen hours and eating only during an eight hour window. Most people who follow this diet choose to eat between 10am and 6pm and are pretty much skipping breakfast and having an early dinner.
So what does the research tell us about the benefits of intermittent fasting? From a weight loss and cardio-metabolic health perspective, intermittent fasting shows good results. Studies have found in overweight and obese people fasting can result in significant weight loss which in turn improved blood glucose and insulin levels, blood pressure, cholesterol and blood fats.
But when compared to a continuous eating pattern short-term studies indicate equivalent weight loss and improvements in cardio-metabolic risks. So neither eating pattern is superior as long as there is a reduction in the total amount of energy consumed, around 25%, similar results are found.
As with any fad diet or eating pattern, success comes from compliance and adherence. As I have mentioned before, making huge changes over a short period of time may bring about the best changes but it’s the ability to maintain those changes which is the hardest part. Studies have found those who have been following an intermittent fasting diet had stronger feelings of hunger and a larger weight regain. The hunger is understandable, especially during the fasting periods, the weight regain is standard as most people regain weight after going on a diet.
So if you are seriously considering trying intermittent fasting as a dietary pattern you think it may be able to sustain for life, there is no doubt it works in terms of weight loss and improving overall health. But it is important not to ignore the basic physiological drive to eat and how hard it can be going through periods of fasting or days with reduced food intake.
Sustainable dietary approaches should be satiating, they should meet nutritional requirements, promote healthy body composition and ensure long-term safety and adherence. If you can find a diet or eating pattern which ticks all the boxes then you are on to a winner.