"but if you eat nothing but meat, it is pretty much also keto as meat has no carbs"
-No, it is not keto. It is a common misconception that eating mostly meat is considered keto. Keto requires around 80% dietary fat and smaller amounts of protein. Via a process called gluconeogenesis excess protein get converted in carbs which will raise blood glucose levels and keep someone out of ketosis. So, all meat does not mean no carbs.
"carbs are what your body uses for energy"
-This is why the body converts protein in carbs. Protein and amino acids are not converted into ATP, but carbs and fat are. If you are in ketosis the body is primarily using ketones and fatty acids as energy not carbs.
"lots of people who go keto spend around 6 weeks tired out, colder than normal and some other stuff as the body starts to adapt - it's often referred to as the "keto flu", but it seems like this would apply to a meat-only diet."
-While the "keto flu" is the initial adaptation period where your body starts using ketones and fatty acids as its primary source of energy instead of carbs the OP has been on the diet for ten months. Again, all meat is not keto. However, there could be an instance of a transient ketogenic state depending on what, when and how much the OP is eating.
"meat also has lots of cholesterol, so it can cause blockage, which limits blood flow and can also lead to cold hands and feet."
-No, if there was a true blockage the tissue getting supplied blood by the blocked vessel would die and that would be a much larger issue. Not all meat contains a lot of cholesterol. Not all cholesterol is bad. Blood tests to measure lipid levels are key here to ensure no long term damage is being done.
A recommendation is to measure ketone and blood glucose levels over a few weeks to get an idea of how the body is processing the diet. That way you can verify if or when you are in ketosis and if that is desirable. Gym logic and speculation is simply that. Track biological data over time and adjust based on that data if needed.
-No, it is not keto. It is a common misconception that eating mostly meat is considered keto. Keto requires around 80% dietary fat and smaller amounts of protein. Via a process called gluconeogenesis excess protein get converted in carbs which will raise blood glucose levels and keep someone out of ketosis. So, all meat does not mean no carbs.
"carbs are what your body uses for energy"
-This is why the body converts protein in carbs. Protein and amino acids are not converted into ATP, but carbs and fat are. If you are in ketosis the body is primarily using ketones and fatty acids as energy not carbs.
"lots of people who go keto spend around 6 weeks tired out, colder than normal and some other stuff as the body starts to adapt - it's often referred to as the "keto flu", but it seems like this would apply to a meat-only diet."
-While the "keto flu" is the initial adaptation period where your body starts using ketones and fatty acids as its primary source of energy instead of carbs the OP has been on the diet for ten months. Again, all meat is not keto. However, there could be an instance of a transient ketogenic state depending on what, when and how much the OP is eating.
"meat also has lots of cholesterol, so it can cause blockage, which limits blood flow and can also lead to cold hands and feet."
-No, if there was a true blockage the tissue getting supplied blood by the blocked vessel would die and that would be a much larger issue. Not all meat contains a lot of cholesterol. Not all cholesterol is bad. Blood tests to measure lipid levels are key here to ensure no long term damage is being done.
A recommendation is to measure ketone and blood glucose levels over a few weeks to get an idea of how the body is processing the diet. That way you can verify if or when you are in ketosis and if that is desirable. Gym logic and speculation is simply that. Track biological data over time and adjust based on that data if needed.
Indeed they are vegetarian! Please tell me you have at least gone to a doctor for a check up or screening in those thirty years 
