eidos said:
I once knew a chef who passed away from heart failure during a serious weight-loss regimen, and this was despite having medical oversight.
So yes, it does happen.
This is exactly why having medical supervision matters. At minimum, you need blood work, blood pressure monitoring, and an ECG.
How fast you lose weight should be measured as a percentage of where you started. Dropping 5 pounds when you begin at 400 is not equivalent to dropping 5 pounds when you begin at 150.
If you're not experiencing an irregular heartbeat, elevated blood pressure, or severe tiredness, you can take some comfort. But issues with the kidneys or liver won't show up without testing. The pancreas and gallbladder can also be impacted. A competent doctor can keep an eye on these things.
Trouble can occur when fat has accumulated in the body over many years, and during that time, the person has been around solvents that dissolve in fat. That list includes paints, cleaning agents, gasoline, insecticides, and pesticides, among others. These can get released into the system and trigger acute poisoning.
If you've gassed up your car occasionally or painted a room or two at home, that's not a concern. What we're discussing is repeated and ongoing exposure.