Read the above replies twice... maybe three times.
Educate yourself. Experiment. The cautious part of me says see a doctor.
Sooo many variables. I recently started riding at the end of this past spring. I started out with plain water, which was ok. When the heat wave hit, in Florida no less, I started riding pre-dawn and added sugar/lytes to my hydration. At the end of summer I was able to back off the sugar, didn't back off the lytes, and gained 5-10 pounds in water weight. I am not sweating near as much. Now I'm going light on the sugar and lytes and need half the volume of water with 50% more ride.
I bonked from the get go today because I lean towards a low carb diet. And I went super low carb over the weekend and yesterday, when I rode 32 and then another 32 miles today. Today it was likely a combo of the cold combined with high humidity and a low personal glycogen store. Drinking more water only made me queasy.
Afterwards my body craved bananas, ate 3, honey and sprouted grain bread after the ride. This was in addition to low fat greek yogurt and roast beef.
I feel good now.
So. Safe route is consult a doctor. But you can't go wrong with educating yourself, obtaining personal data (BP, pulse, glucose level etc) and acting accordingly.
Hope you figure this out. Safe riding.
It is amazing how much of our physiology is trainable. The Badwater 135 is a real thing. That said, there are limits. Riders have died both from hyponatremia and from heat stroke. It's good to familiarize oneself with the symptoms of both because there are limits.
The main noticeable symptom of heat stroke for a cyclist is the cessation of sweating. I watch my forearms, have seen it happen, found water in time. The cause is lack of water. The fix is water and shade.
Hyponatremia is trickier. Cyclists have died because they didn't recognize it: dizziness, fatigue, lethargy, confusion, malaise, nausea, or
thirst. The cause is too much plain water. The fix is electrolytes.