Please forgive me, but, the misuse of the following words is driving me insane. The issue is mine. The goal is to understand each other. Moving on now. Again, forgive me.
Regimen - a regulated course, as of diet, exercise, or manner of living, intended to preserve or restore health or to attain some result.
Regime - a mode or system of rule or government
Regiment - a unit of ground forces, consisting of two or more battalions or battle groups, a headquarters unit, and certain supporting units
Not forgiven… there is no room in this community for pet peeves!!! 
As my grandmother never used to say… “The regime set it’s best regiment on a new regimen”… and it was KETO!!
I’m not sure why but I always saw regime being used in place of regimen when the speaker was from the UK. Never understood it, because regime to me means what it means to you.
I’m a word nerd. I can’t help it. Trying not to be a jerk but I’ve put off saying something for about six months.
Never mind.
regime
NOUN
1A government, especially an authoritarian one.
‘ideological opponents of the regime’
More example sentencesSynonyms
2A system or ordered way of doing things.
‘detention centres with a very tough physical regime’
‘a tax regime’
More example sentencesSynonyms
2.1 A coordinated programme for the promotion or restoration of health; a regimen.
‘a low-calorie, low-fat regime’
More example sentences
2.2 The conditions under which a scientific or industrial process occurs.
Example sentences
That’s the problem with the English language… constantly evolving and general use becomes accepted use/dictionary use so the rules you learned at school are often no longer restrictively valid.
There are whole new written and spoken grammars and vocabularies that are in common use around the English speaking world and these days restriction to ‘Victorian’ standards just restricts some people from understanding more people. For instance there are some folks on here that write in txt speak with (to me) absurd word contractions and letter dropping, illegitimate sentence structure (if any), little valid punctuation etc. but I’ve got to ‘suck it up’ if I want to participate (though I don’t have to write like that)
Two nations divided by a common language 
I am from the uk, and will cheerfully continue to type ‘regime’ rather than ‘regimen’. Probably for two reasons
1 i have always done so
2 it is quicker and easier than typing ‘regimen’
I’m all for minimum effort.
Although i do have a few pet peeves myself…
It should be ‘different from’ rather than ‘different to’. That is a bit frustrating to read.
And my own inability to spell ‘recieve’ correctly drives me mad. 
The biggest problem I find with its/it’s these days is auto-correct making inappropriate changes…
I am also a grammar nerd/snob. How about simple homonyms like “to”, “two”, and “too”? Or “their”, “they’re”, and “there”? Not necessarily on this forum, but on the internet in general, it amazes me how rarely these are used correctly! How was that for a run on sentence?
The grammatically erroneous uses of “should of”, “would of” and “could of” are my pet peeves. It’s like nails scratching on a chalk board, but for my eyes. 
Hang on now. We could reasonably say Keto is a regime. We have President Richard and Prime Minister Carl who have given us a place to live. We can live by the system of rule that is given to us by Ministers for Science Fung et al. Indeed with have a good regiment of members who wage war with the heathens who disparage Keto.
The restraint! . If you could jump on every bit of (non-typo) grammer slaughter in the forum it would lower my cortisol and help me lose weight. TYSM
