The Case for Skipping Breakfast
Dr Mindy Pelz argues that breakfast being "the most important meal" is a claim with surprisingly thin evidence. What actually happens when you extend your overnight fast - and who should avoid it.
The idea that breakfast is the most important meal of the day has been repeated so often that it feels like established science. It isn't. The phrase was coined by cereal companies in the early twentieth century as a marketing strategy, and while there's some research supporting regular breakfast for children and athletes, the blanket prescription to eat within an hour of waking has remarkably little evidence behind it for the average adult.
Dr Mindy Pelz, a nutrition and functional medicine expert who has become one of the most cited voices in the fasting space, makes a straightforward case: for many people, pushing back their first meal isn't deprivation - it's giving the body time to do repair work that eating interrupts. The broader research on when you eat mattering as much as what you eat backs this up at the circadian level too.
What Happens When You Stop Eating
When you eat, your body uses glucose - blood sugar - as its primary fuel. Insulin rises to manage the glucose, and fat storage is prioritised. When you stop eating and your glucose and insulin levels drop, the body gradually shifts to burning stored fat for energy, producing ketones in the process. This metabolic switch isn't instant - it typically begins somewhere around the 12-to-14-hour mark of a fast, which is why sleeping through most of it makes the process painless for most people.
Pelz outlines a progression of benefits based on fasting duration:
- 12-16 hours - Basic fat-burning kicks in, insulin drops, ketone production begins
- 17 hours - Autophagy accelerates: the body starts actively recycling damaged cells and proteins
- 24 hours - Intestinal stem cells begin rebooting, which Pelz describes as a gut reset
- 36 hours - Significant fat-burning; growth hormone increases
- 48 hours - Dopamine system reset; may help break patterns of compulsive eating
For most people, the practical sweet spot is 14-16 hours: skip breakfast, eat lunch as your first meal, and finish dinner by 7 or 8pm. That's it. No special foods, no supplements, no subscription box.
Only 12% of American adults are considered metabolically healthy by clinical standards - meaning their blood glucose, blood pressure, cholesterol, waist circumference, and triglycerides are all in the normal range without medication. [Metabolic Syndrome and Related Disorders, 2018]
Autophagy: The Body's Recycling System
The word "autophagy" comes from the Greek for "self-eating." It's the process by which your cells identify damaged or dysfunctional components - misfolded proteins, broken mitochondria, accumulated cellular debris - and break them down for parts. The process accelerates significantly during fasting, particularly after the 17-hour mark.
Yoshinori Ohsumi won the Nobel Prize in Medicine in 2016 for his research on the mechanisms of autophagy. The emerging understanding is that this cellular cleanup process is suppressed when insulin is elevated - which is to say, when you're eating frequently throughout the day. Extending the window without food gives your cells time to do maintenance that constant snacking prevents. For a deeper look at the cellular timeline, see what actually happens after 17 hours without food.
Who Shouldn't Fast
This is where nuance matters - and where a lot of fasting advocates fail. Pelz herself is clear that fasting isn't appropriate for everyone. Pregnant or breastfeeding women, people with a history of eating disorders, children and teenagers, and anyone with type 1 diabetes should not be fasting without direct medical supervision. People on medication for blood sugar management need to consult their doctor before changing meal timing, because the interaction between fasting and medication dosing can be dangerous.
Pelz also notes that women's hormonal cycles affect how fasting lands. During the week before menstruation, when progesterone is high and the body is prioritising different metabolic processes, aggressive fasting may cause more stress than benefit. The advice isn't one-size-fits-all, and anyone selling it as such is oversimplifying the biology.
The Practical Version
If you're curious about intermittent fasting and don't fall into the groups above, the lowest-risk entry point is straightforward: finish dinner by 8pm and don't eat again until noon the next day. That's a 16-hour fast. Black coffee, tea, and water don't break it. Your body is already fasting while you sleep - you're just extending that window by a few hours on either side. (If you're in India and weighing the cultural context, we've covered what Luke Coutinho gets right and wrong about IF in India separately.)
Give it two weeks before judging. The first few days involve a recalibration period where morning hunger feels pronounced. By the second week, most people report that the hunger window shifts and they feel more alert and less distracted in the morning than they did when eating breakfast. Whether that's physiological or partly psychological is debated - but the metabolic data on insulin reduction and fat oxidation during 16-hour fasts is well documented.