If you just do some exercise regularly and eat halfways right you are already way ahead of 90% of the population . It always amazes me to learn that a lot of people do absolutely nothing.
I think many people are took quick to not push through something that is just a little uncomfortable. For example, a healthy person doing a short fast (24/48 hours) once in awhile teaches you what it feels like to really be hungry, know that feeling goes away, and know you can operate just fine.
Once you start eating your body wants more food. Eat nothing before training and you're still in warrior mode.
Running/swimming/cycling: anything at or around low aerobic threshold (Friel HR zones 1, 2, or 3)
Strength: Endurance-focused compound primary exercises (e.g. squats, deadlifts); any form of auxiliary exercises (planks, bicep curls, etc.)
Anything more than that and I need to wait at least 2-3 hours after waking up (e.g. cardio in Friel zones 4, 5a, 5b, 5c or max-strength-focused primary compound exercises.)
Ramadan is a widely held fasting period that impacts millions of lives, many of whom train power/strength/endurance while fasted under the conditions described above. This has been studied in depth, with oodles of peer-verified and unequivocal real-world data showing it's totally possible and not noticeably harmful (technically, the studies show it to me mildly beneficial...). In a training context the hormonal boosts are impressive and much more noticeable while fasted.
Your body has a learned point where it expects food. That learned point can be moved through habit. Humans, and mammals in general, are meant to thrive in the wild. Our physicalities are not precious. We do not turn into Gremlins if we are not fed before 10:00AM.
Not a week ago I did a mountain trek that streched 6 hours past expected. At 9:30PM, at the tail end of an unplanned 30 hour fast, after a 10 hour 500 vertical meter hike (with a kid on my shoulders!), I was so over-energized I had to take a jog to wind-down. Hunger and energy are much more about habits than we've been raised to understand.
Not only is it not uncomfortable, I feel _way_ better before/during/after working out.
Firstly: the food in your mouth is not used for your workout. You work out with food already digested and put in your muscles. Our biology is not precious, jungle-warrior neanderthals did turn into skeletal waifs if accidentally they hunted before noon without a BCAA-rich recovery shake. Nothing about morning training is energy, it is all habit, comfort, and hormones.
The primary issue, for most people (including me earlier), is that they train "before breakfast" and not "fasted". Important distinction. Hunger (and the hormone that causes it), comes in manageable 20-30 minute waves. If you do nothing it will pass. Most people take a banana, or some milk in their coffee, or a "little snack" before trainin. That breaks the fast. That is "break-fast", and it starts your body expecting food. So if you don't break your fast, you aren't exciting those hormones and insulin, so your body is ready to roll focused on the task at hand.
Secondarily is hormones. When you are fasted your body makes lots of great focus hormones. It also gives you extra HGH. Training also delivers HGH. Training additionaly delivers bombs of happy-hormones, and go-rip-the-world-a-new-one hormones. If you're fasted, you are more sensitive to those hormones, meaning you feel better. If you're fasted your low insulin also lets your body get as much fat-energy as it needs, so your energy levels can be amazing.
Outside of that is simple comfort and habit. The time your body expects food, the "engrained eating time", is adaptable. Having a lower baseline insulin, and a lower-carb diet, that minimizes "hangry" feelings and snack cravings will also be a huge help. Combine the two and you've got a recipe for insanely fun work outs with no hunger issues and better energy than otherwise.
Black coffee, water, and nothing caloric before training. It's night and day :)
I take my daily L-carnitine during my feeding window at night.
There are different levels of fast, for most people most of the time (ie those looking for weight loss), taking a pill during the fast should be just fine (as long as you're under 30-50 calories).
That said, personally I do not like taking pills during my fast, as it will wake my stomach up and cause some hunger. Same thing with gum and stuff, but that's all individual preference :)