Hi Vero and welcome:

16:8 is also known as the 8 Hour Diet. I think the book came out in 2013 and was very popular for awhile and then faded. The book claims that you can eat as much of anything you want and as long as you eat it all in 8 hours or less you will lose 20, 40, 60 or more pounds – even if you only do 16:8 three days a week. According to the book, the secret that allows you to eat, say, 3000 cal. a day when your TDEE is 1800 and still lose weight, is that by going 16 hours without eating any food your body will go into a ‘fat burning mode’ that will counteract all of the calories you are eating. People soon found it didn’t work, but interest in the diet has been revived as it has been rebranded as an intermittent fasting diet.

Today, knowledgeable people know the claims of the book are inaccurate. 16:8 has become a description of when people eat – they eat in an eight hour eating window. The only way they lose weight is if they eat less than their TDEE in that window – if they eat more, they gain weight. There are no dietary ‘rules’ that go with it, it is anything you want it to be. Basically, it is a 7 day a week lower calorie diet (if you eat less than your TDEE each day).

As there are no calorie restrictions or food requirements that come with the 16:8 name, anyone can say they are following 16:8 and you will have no idea of what they are talking about unless they also describe what, how much and how often they are eating during their 8 hour eating window. For instance, it is not unusual for people on 5:2 to eat only one meal on their diet days. That could be described as following 16:8, but it could also be described as following 23:1, 19:5, or 12:12 – all equally meaningless. They could be eating 500 cal. at that meal, or they could be on the warrior diet and eating 2500 cal. – although hopefully not on a diet day, but you won’t know by the name.

There is a recent TV experiment going around that indicates there might be some benefit to eating in shorter time periods. However the experiment was hardly scientific. The people involved each had different diets and different calorie intakes. No weight loss was reported for either the ‘control’ group or the 8 person group on the restricted eating regimen. The benefits found could easily be attributed to factors other than not eating an additional three hours a day, including ‘different’ eating by the group that had the restricted window – they were only tracked by how much they ate. There is no way to know. Pretty much a meaningless exercise from a scientific standpoint, but good TV. However, it does highlight why some people like 16:8. Some people feel it helps them not snack as much, so they eat less. The concept of the window seems to help them focus on when and how much they are eating and by doing so helps them control how much they are eating. My observation is that if people start 16:8 for weight loss, they like it at the start, but within a month or two give it up because they aren’t losing weight and they don’t like having to arrange their lives by when they can eat.

There are no other studies I am aware of that show any benefit of following an ‘eating window’ way of eating. But there are no studies that show it is harmful, either. You might see if there are any 16:8 forums or websites that can help you decide which method you like best.

Good Luck!

The answer to your question is there are no scientific studies showing that 16:8 works or doesn’t.

The overall idea may sound valid but the only way to lose weight is to consume less energy (calories) than you expend. I gave 16:8 a try and it didn’t work for me. The simple reason being I ate more in the eight hour window and two meals than I expended in the 16 hour not eating period. Heck I can consume more in an hour than I expend in a day.

Some people find it beneficial it has to be personal. If it doesn’t work then do 5:2 it is proven to work for weight loss.

Hi Vero:

Your resting metabolic rate is irrelevant for weight loss. TDEE is quite important.

If you look at any TDEE calculator you will see no input for what or how much you eat. That information is unnecessary to estimate either TDEE or BMR. That also means that information does not affect BMR or TDEE.

Very little affects BMR – not even exercise. What does affect it is weight loss or gain – BMR goes down or up materially with those factors.

Although Dr. Atkins speculated that there might be a ‘metabolic advantage’ by eating a high fat/protein diet, it was never proven. The diet neither increased nor decreased the person’s ‘metabolic rate’. Research shows that people following the Atkins diet are eating a low calorie diet and the reduction in calories causes the weight loss, as is the case with all successful weight loss diets.

For the same reasons, 5:2 does not affect the BMR except by causing weight loss. Simply eating less has no effect on the BMR or TDEE at all.

Good Luck!

Vero,

If to you 16:8 means skipping breakfast and then not compensating by eating more later, you will have ‘saved’ your breakfast calories. That may or may not be one third calories. For me that would be perhaps 400 calories ‘saved’, which is a 1/4 – 1/5 TDEE. Over the longer-term, this should result in weight loss. So in this scenario you are in the realms of daily caloric restriction. However, it is still possible to overeat in an 8 hour window. So it’s really going to depend on whether you’re happy restricting yourself on a daily basis.

The beauty of 5:2 is that you don’t need to restrict every day, only 2 days out of 7. So for most people in terms of compliance it’s much simpler.

In my experience, 16:8 can be sufficient for weight maintenance (and possibly weight loss over longer time periods; unfortunately when I was my lightest as an adult, and an inadvertent 16:8er, I wasn’t monitoring weight or exercise or calories…); 5:2 plus 16:8 plus no added sugar/ low refined carbs definitely works for me for weight loss.

Hi Vero,
Michael has a programme called trust me I’m a doctor available on bbc I player. The research is now compelling on how good for you eating in a small window and fasting the rest.
If you’d like to email me, I could go into greater detail. I’ve list 16lbs since 1/1/16