When following the one meal a day intermittent fasting protocol, can you really eat whatever you want and still lose weight?
What is One Meal a Day Intermittent Fasting?
Confusingly, there are different ways to interpret what is meant by “one meal a day”. There’s no doubt about the length of a day as it’s absolutely fixed by the rotation of the Earth at 24 hours long. Whereas the definition of what a meal is can vary depending on who you ask.
Is a meal all you can eat without leaving the table? What if you stayed at the table for 6 hours and ate 2 large plates of food each piled high with calorie dense goodies? Is a meal all you can fit onto one plate only? What size plate? What about starters and desserts? If you can finish your meal in under an hour then how is one meal a day any different from an intermittent fasting protocol based on a 23 hour daily fast?
These are all valid considerations and we need to remember that we are all individuals with different bodies, different lifestyles, different nutritional requirements and different goals.
Increasing Insulin Sensitivity
One of benefits of intermittent fasting is its potential for increasing insulin sensitivity¹ (insulin resistance is associated with type 2 diabetes) which is achieved by reducing the body’s frequency of exposure to elevated insulin levels caused by the ingestion of food energy primarily from carbohydrate and protein sources. If one of our goals is to maximise this benefit then a longer period of fasting will provide more of that and conversely a longer feeding window will undermine it. In other words, spreading your “one meal” across several hours will not provide as much benefit in regard to increasing insulin sensitivity as eating your one meal within a single hour.
Eating as Much as You Want
When it comes to the content of your meal, can you really have as much quantity of whatever you want? I would suggest it’s possible, but it depends on what it is you want and what your body needs. Everybody’s definition of what they want to eat will vary from person to person. Some people might crave lower calorie-dense foods than others whilst maintaining a higher total daily energy expenditure (TDEE). One person’s “whatever they want to eat” could differ from another person’s by several thousand calories. If their TDEEs were the same then one person could lose weight whilst the other gained even though they were both eating whatever they wanted for their one meal.
Clearly, a subjective term such as “whatever you want to eat” cannot be universally applied to one and all. To be objective, we need to consider the balance of energy intake and energy usage at an individual level. An excess of energy intake which isn’t balanced by a corresponding increase in energy usage means the body has to store that excess away and once glycogen stores are full then our bodies will store excess energy as body fat.
It’s also important to remember that what a person wants to eat can change as appetite control improves with intermittent fasting². A person who starts off craving sugary foods might find that desire blunted after months of one meal a day. Not only can the definition of eating whatever you want vary across people, but also across time for the same person.
Meeting Nutritional Needs
Energy for the body to use as fuel isn’t the only thing we should be concerned about as we also have macronutrient needs to be met and again these are requirements specific to individuals. Carbohydrates are the body’s primary source of energy whereas proteins and fats are required for many essential bodily processes such as the repair of damaged tissue and production of hormones. There are essential amino acids (what protein is composed of) and essential fats which the body cannot produce and therefore must be supplied by dietary means.
Clearly, this means we wouldn’t survive on a diet consisting solely of carbohydrates regardless of whether we’re intermittently fasting or not.
Can You Eat Whatever You Want?
The question which should be asked is not so much whether you can eat whatever you want whilst following one meal a day intermittent fasting, but rather whether what you want you to eat meets your nutritional requirements whilst helping you achieve your goals. If what you want to eat does this then yes, you can eat whatever you want with one meal a day.
[1] Furmli S, Elmasry R, Ramos M, Fung J. Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin. BMJ Case Rep. 2018;2018:bcr2017221854. Published 2018 Oct 9. doi:10.1136/bcr-2017–221854
[2] Elizabeth F. Sutton, Robbie Beyl, Kate S. Early, William T. Cefalu, Eric Ravussin, Courtney M. Peterson, Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. (http://www.sciencedirect.com/science/article/pii/S1550413118302535)
