How often do we need calories? Would one 8000 calorie meal every four days replace four 2000 calorie meals every day? Is four 500 calorie meals a day better than one 2000 calorie meal a day?


I was wondering this the other day. It’s similar I think to “How efficient is out digestive system”. Is there an optimal number of calories to take in every X amount of time to maintain a steady…calorie intake? Energy generation?

In: Biology

Generally your digestive system works within a 6-8 hour time frame to go from eating the food to excreting it. It’s not 100% thorough with absorbing all the nutrients, fats and water, though, so if you were to eat 8000 calories at once, your body is only going to absorb a portion of that, pass any excess through without absorbing it, and will need more food several hours later.

tldr- our body is optimised to eat roughly 1500-3000 calories a day, so eating more than that will just pass through your system

the short answer, your body can absorb about 240 calories of carbs an hour, this varies a bit but as a general number. So, It possible that eating massive meals like that you might end up with some of the calories passing through you entirely.

But it likely wouldn’t be healthy for a multitude of reasons, which pushing your body back and forth from complete 0 calories to a massive amount of food would probably take its stole as it might shock the digestive system (people who have gone without food/starving actually eat very small meals when recovering, because eating a lot at once stresses the digestive system out and makes many throw it back up)

The other big issue is we need to intake more than just calories a day, a lot of your vitamins and minerals, salts, potassium, etc. that you need that body cant really store it,so you need to regularly be refilling your stores of them.

Depends on the person as well as their metabolism. But in theory, no to your first question; our bodies just do not work like that. The stomach is not like a gas tank in which case one could upgrade to a larger size tank. Yes to the second question however. Because this is more fitting to the human nutritional model. When you consume calories, you usually intend to replace what has been used as well as prepare for what is about to be used. It’s not so much a ‘get to zero (0) then replenish with 500-2000’ and carry on. More like, expend 350 calories then start to replace that amount while you still have roughly 150 left from the previous 500 you already consumed earlier.

As far as optimal number of calories, that depends on the individuals bodily requirements; larger people require more than smaller people. And to this, larger is more proportionate to body mass index; the ratio of fat to muscle that one carries. Even height can be a factor so there really is no prejudice in my statement as far as ‘larger/smaller beings’. We all need our own moderation. Obesity is more of a health issue seeing as one of this nature usually is not really expending calories in a ‘fashionable’ way; eating just to consume what one loves to eat for the sake of satisfying mental craving is just gorging for the most part. Where as body builders eventually push their body beyond their naturally sensible limits for the result of massive muscles. At that point, yes, these individuals require a higher caloric intake simply because some or most of their work outs will burn hundreds of calories in a matter of one of more hours. I would include rather serious athletes sort of in the middle of a ‘normally healthy being’ and ‘body builder’. For instance Michael Phelps, the Olympic swimmer. Not a body builder, but due to the nature of their sport expertise, he really goes through the calories a bit more than normal and thus has reason for higher portion meals.

It’s really a matter of finding that happy balance depending on your body type and the activities performed. An even more honest answer from my own perspective? It’s never ‘perfect’. And honestly, I hardly really pay full attention or track my dieting schedule. Some days I only eat a light breakfast, light lunch, and a moderate-normal dinner. Where as other days I eat like a horse; big breakfast, basically a normal size lunch as brunch/lunch with maybe a snack to get by until dinner, followed by a normal size dinner and perhaps something small later that evening (like a peanut butter jelly with a protein drink). The latter being days where I workout/lift a whole bunch. The best I can do to moderate my diet without feeling like I’m on a weight watchers nazi diet is make sure not to eat too much red meat too often. Breakfast will mostly consist of oatmeal/cereal or perhaps the traditional eggs/bacon/toast. Mid day snacks are normally fruits, yogurt, etc. I like to consume at least one large container of kefir per month which stretches out to, at most, 10 days (small portions usually with breakfast). Lunch is almost always a turkey/bacon/gouda on mini na’an perhaps with more fruit if I’m really that hungry. Or some sort of left over, especially if it’s chicken (or beef on work out days). And dinner is a collective between whatever my family and I can decide on together or I’ll go out/cook my own meal once I know they are taking care of themselves for that evening. And it can be just about anything as long as it coincides with what I’ve had that day/lately. For instance, I rarely eat steaks back to back nights. Same with chicken as it will make me get lazy for some reason. I love some types of fish however I can still get hungry again after dining on fish unless I go to sleep within a timely fashion. Otherwise, I know I am going to wake up hungry which isn’t really a bother to me. Hope this helps!

So just starting with some basics on how much energy you have available within body at all time. Average body fat is 18–24% in man and 25-31% in woman ([Average body fat]( Average US man is 69.0 inches (5ft 9in, ) tall and weights 197.8 pounds, for women it is 63.6 in, 170.5 pounds ([Average body measurements](

When you put these measurements into TDE (total daily expenditure) calorie calculator (e.g. this [one](, you’ll get for 25 year old male with these measurements, 20% of body fat and sedentary office job 2297 calories per day. 1914 calories of that is BMR (basal metabolic rate). These are the calories the body will need no matter what, just to keep lights on.

20% of 197.8 is 39.56 pounds of fat, which at 3500 calories per pound gives you 138,460 stored calories. At calculated TDE this is enough for 60 days.

You have also some glucose stored in form of glycogen in your muscle and liver. The amount of glycogen stores depends on many things, like your training status, metabolic balance and eating, but on average you have about 100g in liver and additional 400g in skeletal muscle. At 4 cal per g, that gives you ~2000 cal stored as carbohydrate. Muscle glycogen can be only used directly in the muscle and not transported out, while liver glycogen serves to balance glucose amount in the blood.

The final macro-nutrient, protein and its building blocks amino acids do not have any storage mechanisms as such, they are just present in all cells and obviously a lot of total amount is again in skeletal muscle.

So finally to your question. 8000 calories every 4 days would be enough to replenish the calories, but more than likely wouldn’t be optimal eating strategy. Disregarding the problem of just digesting all that food, which our digestive tract can do, but will probably have some problems with, you will run out of stored glycogen needed to keep stable blood glucose level.

Your body will switch to “backup system” of feeding your brain with ketones, generated from fat. This will happen generally in about 2-3 days, and is not that pleasant if you are not used to this. Then your eat your huge meal on day 4, switch back to glucose, inducing probably huge insulin spikes. Not at all healthy.
If you were on high fat ketogenic diet, you would probably avoid this problem, but would still face trouble of loading your digestive system with a lot of fat and protein every 4 days.

You will also have problems for example with training/demanding physical activity. You’ll break down some muscle and need to replace it. Now you didn’t eat for 3 days and your circulating amino acid levels are low. Your body has to take them from some other part of the body, e.g. you train your biceps and amino acids will be provided by your leg muscles. Next day you go for your leg day and amino acids will be taken from you pecs. Pointless. Then you eat your 8000 calories, including a lot of protein. But there is no way to store amino acids outside of the muscle and muscle won’t be build that fast. So most of the amino acids will be just burned as fuel or deaminated and converted to stored glycogen/fat.

Now 4x 500 calorie meals a day – probably OK, it was preferred strategy by bodybuilders for long (sometime going to 6 meals/snacks or more), exactly because they were afraid of running out of readily available amino acids for muscle building. But each meal, if it contains sugars, will also spike your insulin and there are some indications it’s not the healthiest thing to do.

Finally one meal a day – if your digestive tract can handle it, this should be OK. Some people prefer doing OMAD (One Meal a Day). You provide your body with some potential benefits of intermittent fasting, such as low and stable insulin level, some autophagy activation and also if you time it right, it should support your natural circadian rhythms and improve your sleep. Digesting such large meal still takes some time and amino acids will be released from digested protein over several hours.

What is absolutely best way to distribute your calories in time is not completely clear and it might differ based on what you want to optimize for (general health and longevity, maximum athletic performance), but probably is somewhere in that range of 1-4 meals per day, with maybe some longer fast from time to time.