How serious is the "starvation mode" claim about consuming less than 1!

Everybody is different. I'm no doctor but I'd wager that if you aren't losing any muscle mass or other lean body tissue, and you don't feel constant hunger, dizziness or fatigue, and nothing else unhealthy is happening to you, then your diet is fine for you. Those are the primary symptoms of undereating/starving. If you are in good health, there's no reason to forcefeed yourself simply to make a calorie level that is a general guideline.

But if you are experiencing these symptoms and you just refuse to eat no matter how you feel or what's happening to you, then you are in starvation mode and you have an eating disorder. and are denying it.

Only you know what's really happening on your end of the interwebs.

Yes it is true, but for someone like you what it will do is slow down your metabolism and make it harder to lose weight. BAck when we were cavemen, we had good days and bad days when it came to food. BAd days we hardly ate anything, and good days we killed a mammoth. So today, you need to keep your metabolism up so that your body doesn't think it is starving and will be more willing to give up its precious fat. So if you eat 6 meals a day, 3 at 400 calories and 3 at 100 calories you will be fine and you will lose weight.

I dont think there is a magic number in which your body starts storing fat due to starvation, I think being consistent is important and making sure your body is getting what it needs to function, you need carbs and sugars the same way you need vitamin A and B, just be sure your eating a variety to prevent your body from feeling "starved" or deprived

It's not a magic cutoff, but if you do it somewhat consistently, your body will respond by slowing your metabolism to conserve fat.

Also, it does vary with body type. If you're small and female, you won't need as many calories as someone larger or male.

if you consistently try to go below 1200 cals a day; you will eventually force your body into starvation mode. your body is not interested in your goals. it just wants fuel to survive.

It’s a very serious condition as its name implies...STARVATION mode...gosh, I’m kidding! It is the year 2011 (I live in the sheltered US, a fat country...70% and going up)!
For me it’s like a math thing (I like numbers and they always align like dominoes for me).
1,200 calories is the BMR (Basal Metabolic Rate) of a 60 years old, 5’5 and 120lbs woman.
If you’re younger, shorter or bigger, you need more calories to cover your BMR. Even that 60 years old, 5’5 and 120lbs woman would need to eat a few hundred more calories for exercising in order to maintain her muscle mass (use it or lose it).
Like...I don’t know...if you’re a 17 years old girl, 5’6 and 164lbs then you would have a 1,600 calories BMR. Then go send your metabolism down the drain by eating a few hundred calories and not even being able to blame it on the German, the Chinese or a tonsillitis.

Now your BMR is a DAILY average. You can eat 1,000 calories on one day (mostly your rest days) and 1,500 calories the next because you have a lot of energy to exercise and needed an extra snack (if you swim, you know what I mean). Now try not to mix up your apples and your oranges (like calorie intake and calories expenditures). Your calorie intake is what you eat and your calorie expenditure is your BMR (like 1,600 calories for you) + your growth (under 21) + your physical activities...but if you do not eat to cover your physical activities....that is the mother lode. Your body will have to burn fat reserves for exercising.
And not going into details but it does not matter if your body can only burn carbs during anaerobics (as it is anaerobics so fat burning shut down as you cannot use oxygen to process fat cell) or fat reserves after 20 minutes of aerobics...the overall calorie expenditure is what will determine overall fat loss...as I said it is just math. But it’s much easier to eat well so you can use carbs while exercising. People exercising on an empty stomach in the morning are either freaks (7%) or have no choice and do it the hard inefficient way (they cannot wait for 2 hours after breakfast as they have to go to work/school).

Starvation mode can still hit you nowadays because of sickness or eating disorders. I got a lower BMR at 19 because of sickness but it took several months for my body to lower my metabolism (your body is a marvelous adaptable system to save you from starving too early) while I could not eat (I had “inoperable” tonsillitis that I got operated on an unofficial channel...that hurts when you cannot have the anesthetics in the basement of an hospital, strapped to a chair, bleeding like a pig, and fainting a few times, dealing with a lonely medical student).

Hopefully you’re not starving. You’re not in a concentration camp during WW2. At the time, the Chinese would preferably walk you to death or just did not feed you enough (they did not even have enough food for themselves and a handful of rice/day for a couple of years will surely put you in starvation mode, no matter how many bugs you can catch), while the Germans sent you to the gas chambers or worse. Nowadays, you’re not living in a starving African country (you have internet access) and people in starving African countries do not count their calories intake...just get as much as they can whenever that can be and gobble up a live beetle like it’s candy.

During WW2, even free people that were not in concentration camps lived in towns (like beautiful Paris in France) with there were no pets left (all eaten away). You could not get milk, butter, cheese, coffee, meat, eggs, veggies, beans, peas, lentils...you could get lucky or smart and get flour to make bread or pasta. Food was for the occupying German forces. You had to either rely on some rats and rutabaga or move to the country side to farm and hide your crop and your cow(s) and pig(s) and chicken(s) from the hungry Germans.
Some miserable people were the smokers who could not find cigarettes or had to share one with ten other smokers!

Even nowadays, (in the South of the US) some toothless people actually hunt, kill and eat squirrels on a voluntary basis with a fancy accompaniment of wild dandelions salad while having a BI-LO nearby that they do not use except to buy booze and just spending their welfare money on cable TV and booze.

Do not worry too much about “starvation mode” is you’re not in a harsh condition (years of wars, months of diseases, being stuck under a building for several weeks after a tsunami...).

I rely on math. I burn a pound of fat reserves for 3,500 calories of exercising (aerobics and weight trainings, counting the daily calorie expenditure of muscle mass maintenance). I eat my BMR (lowered to 1,200 from 1,250 due you sickness 30 years ago).
My math get smack down to my scale numbers and how I low on the scale, which I don’t really care about...more about how I look and how strong I get...you haven’t getting me started on weight training yet!