Why women need to eat first thing in the morning (and why men don’t)
I used to always workout on an empty stomach because it felt better on my digestive system to exercise without food in it (unless I was doing a really long run or hike). So I’d wake up, drink lots of water, get my 30 minute workout in, shower, then have my matcha and breakfast. I […]
I used to always workout on an empty stomach because it felt better on my digestive system to exercise without food in it (unless I was doing a really long run or hike). So I’d wake up, drink lots of water, get my 30 minute workout in, shower, then have my matcha and breakfast.
I assumed that we’re all different and some women just feel better working out on an empty stomach while others need to eat before.
After listening to Dr. Stacy Sims on various podcasts (all linked in references), I learned that there is a lot of science explaining why women should not exercise (or do anything really) on an empty stomach. So let’s learn why!
Why women shouldn’t hold a long fast
Women and men vary greatly in a lot of ways, and one of those ways is the hypothalamus. This is the control center of your brain – it senses temperature, nutrients, etc…and tells your body to adjust accordingly.
To put it simply, women have a much more sensitive hypothalamus than men due to our more complex hormonal system, especially when it comes to nutrient density.
Both men and women have a natural spike in cortisol 30 minutes after waking up. For women, if you don’t give your body any fuel in that 30 minute window, the hypothalamus senses that you don’t have enough blood sugar or carbohydrate to fuel your muscles and goes into conservation mode. This leads to cortisol levels staying high and fuel getting pulled from your lean mass (muscle and bone).
So the classic routine of “wake up, drink coffee, hit the gym/go for a run, then eat” will just put your body into a stressed state (tired and wired), prevent you from hitting your desired lifting or heavy cardio intensities, and signal your body to break down muscle while you’re trying to build muscle.
For men, their hypothalamus isn’t as sensitive AND they are able to pull energy from their liver and muscle glycogen stores rather than lean mass. There’s a biological reason why men see much better results from fasted work outs.
Eat more to burn fat and reduce cortisol
Eating something within that 30 minute window will signal your brain to lower that spike in cortisol. If you don’t give your body any fuel, whether you’re working out or not, this will cause cortisol to stay elevated, stay in sympathetic “fight or flight” mode, which tells your body to hold onto body fat.
So trying to lose weight by fasting in the morning is counterproductive because it actually signals your body to stay in that sympathetic “fight or flight” mode and hold onto fat.
If you think about evolution, when women couldn’t get in enough calories, their menstrual cycles would stop and they would hold onto fat in order to store calories. Men, on the other hand, would get leaner and stronger because they’re the ones that had to go find the food.
Eat more for better sleep
On top of that, eating in the morning will also help you sleep better at night. If you are bringing your morning cortisol down, over the course of time you’ll have a lower cortisol baseline. This helps get into a parasympathetic (rest and digest) state, which you need for high quality sleep.
If your cortisol is high all the time (from either not eating enough throughout the day or not fasting in the morning), your sympathetic (fight or flight) system will be activated and you won’t get that deep reparative sleep.
Also, when women either don’t eat enough or hold a long fast, they will often wake up in the middle of the night due to low blood sugar.
So make sure you’re eating enough overall and eating something small in that 30 minute waking window to get better sleep.
The best fasting protocol for women and why men do better with fasting
Most fasting data pulls from men because they are a lot easier to study, but when you really look at female specific data, it’s completely different.
According to Dr. Sims, the best fasting protocol for women (of all ages) is to work with your circadian rhythm:
- Don’t eat 2-3 hrs before bed – this will give you a mild overnight fast and put your body in a parasympathetic state for sleep.
- Eat something small within 30 minutes of waking up – to blunt the cortisol peak that happens with waking and to tell your brain that nutrition is on board and you’re ready to take on the day or your workout.
For men, more intense fasting will give more benefits because it activates their parasympathetic (rest and digest) system, gives them better glucose control, more body fat loss, and metabolic flexibility.
For women, it activates our sympathetic (fight or flight) system, which leads to less blood sugar control, higher resting blood glucose, more fat storage, more sympathetic drive (putting the body under stress, impacting sleep and recovery).
Additionally, men can get by with fasted training because they actually use more fat when they are fasted due to their muscle structure and fiber type.
Men’s muscle fibers are more glycolytic (they use glucose as fuel), whereas women have more oxidative fibers (use fat for fuel). So when women don’t give their body enough fuel, the body stores more fat because that’s the preferred fuel for their muscles.
What should you eat in that 30 minute window?
You don’t have to eat a full meal that early in the morning. You just need enough food to let your brain/hypothalamus know that you have nutrition coming in.
According to Dr. Sims, you want about 15g of protein if you’re just doing a strength workout or 15g protein + 30g carb for cardio and strength.
To keep it super simple, I will just eat a couple of scoops of this overnight oats base (I always have this in my fridge!) with some Greek yogurt OR I’ll make a bigger breakfast smoothie and store some of it to have the next morning.
Below are some more ideas:
- Overnight oats – for the busy mom, Dr. Sims suggested breaking your overnight oat breakfast into two. First thing in the morning, eat half with a scoop of greek yogurt and fruit. Later on, eat the rest with more Greek yogurt, fruit, and nuts.
- Mixing protein powder into your morning coffee (click here to see Dr. Sims make her protein coffee) or make a small protein shake.
- Smoothie – make a protein smoothie the day before and drink it in the morning.
- 1/2 cup Greek yogurt with berries and nuts.
- A high-protein muffin or bar.
- 2 cups of bone broth.
Browse the snacks or the breakfast recipes for more ideas.
In summary
So for anyone who normally fasts in the morning or exercises fasted, I hope this has convinced you to switch it up and see how you feel. Since making the switch myself, I have noticed a difference in my energy levels when working out and feeling more calm.
To recap:
Men and women have very different needs when it comes to nutrient density needs and the timing of fueling. This is why women don’t respond well to long fasts, while men see many benefits.
Women should eat something small within 30 minutes of waking up, whether you’re working out after or not.
This will signal the brain that nutrition is coming in, which will reduce your cortisol, putting your body in a parasympathetic (rest and digest) state rather than a sympathetic (fight or flight) state.
If you exercise or go too long without any fuel in the tank, your cortisol will remain high and your body will begin to pull energy out of your lean mass (muscle and bone) and hold onto fat.
The best fasting protocol for women is to avoid eating after dinner and eat something small within 30 minutes of waking up. Eating in tune with your body’s natural rhythm and hormone systems will activate your parasympathetic system for better sleep and lower cortisol.
Lastly, your body will be under stress if you aren’t consuming enough calories throughout the day, which can lead to a lot of problems, one of them being poor sleep and middle of the night wake ups from low blood sugar.
References:
I got all of this information from various podcasts with Dr. Stacy Sims (an exercise physiologist, nutrition scientist, and expert in female-specific nutrition and training for health, performance, and longevity):
leave your comments!