You can go for months and months and months exercising and living on 1400 Calories per day. Your body can easily acclimate to this Calorie level. Women who pledge low Calorie for life in order to gain longevity benefits live on 1400 to 1500 Calories for years and years and years. Men who pledge low Calorie for life are on about 1700 to 1800 Calories. These people are very serious about their high quality food choices 100% of the time. They do not eat a piece of birthday cake on their birthdays; they do not eat a traditional holiday meal on any holiday; etc.
I’ve seen these people and IMO, they don’t look as healthy as those of us who eat more than they do. IMO they look scrawny and old by their 30th birthdays – - – but they are looking forward to celebrating their 100th birthdays (without birthday cake). It is a lifestyle choice they have made and they stick with it.
What does this tell you? You are acclimated to eating 1400 Calories per day. Your body is surviving on that and is thus not in a fat loss mode. It is surviving because it has altered what is called the Bioenergetic Equation that describes how your body allocates your fuels (the food you eat) for survival and reproduction. You are putting less Calories toward body heat production and toward activity than you would at a higher Calorie level. You may or may not notice that you feel colder than you did at a higher Calorie intake. You may or may not notice that you simply move slower and you move less all day long through your activities. You may even be sleeping more than before. You may also be putting less Calories toward egg production, immune system function, tissue repair, and other things.
Any Calorie deficit moves the body’s Bioenergetic Equation to adjust “down”. There are lots of things you can do to fight this adjustment. One important trick of many: make sure the Calorie deficit between energy in (what you eat that is absorbed into the blood stream) and energy out (what you burn or turn into other things like stored glycogen, stored fat, new tissue) isn’t overly large. The experts say that the maximum OK deficit between energy in and energy out is 500 to 1000 Calories per day, values which equate to the one to two pounds of loss per week rate. I think for people who don’t have much to lose, the deficit should be more like 250 or even 200 Calories per week. Another important trick of many that can be used to fight the “acclimation advantage” (LOL! It is a survival advantage even though with all of this food available we don’t look at it as an advantage.) is to not eat the same amount of Calories every day for many days in a row. If you eat maintenance level Calories on some days of the week and deficit level Calories on other days, your body will be less likely to adjust down to the lower Calorie days.
If you want to be super fit and lean, you have to eat and exercise to turn your body into a fat burning machine rather than a fat storing machine.
