What would keep me alive longest: 60,000 calories consisting exclusively of fat, protein or carbohydrate? (Don’t worry, I have plenty of water!)
Other posters may correct me, but:
Doesn’t technically matter, unless you have some other conditions not clearly stated. A calorie is a calorie to the body. That is, regardless of how much energy is literally contained in organic matter, we only count calories that we can actually use. So 100 calories of pasta, dark meat, or lard is all the same. That being said, all have advantages and disadvantages, which is probably one reason we can make use of all of them. If you had to just pick one, I would recommend protein, but only because proteins usually contains more useful micronutrients. If you’re assuming a “pure” ideal food, then it would be irrelevant - although in that case, I’d go for the protein or fat since it “sticks” longer and would probably leave you feeling at least a little less hungry.
The body is pretty good at converting whatever it gets into energy whatever the case, though. If you ration it carefully, you could survive (miserably) for several months. Although you would be seriously weakened by the end.
Another vote for protein … this also has the amino acids vital to survival …
Protein poisoning from a near pure protein diet is a thing
Like what?
Essential amino acids are not micronutrients. And protein on its own does not contain vitamins.
Consumption of a lot of protein could put additional strain on one’s kidneys. And as Astro points out, protein alone can be detrimental in other ways.
Consumption of fats in high proportions seems to promote insulin resistance.
High carb diets can cause fatty liver disease.
If I had to choose one, I’d probably go with high fats, and restrict calories to maintain ideal body weight, while exercising regularly.
But none are really healthy. We’re not evolved to subsist solely on one such source. And if we can’t supplement with vitamins we’ll die soon regardless.
60,000 calories is only about three months of calories on starvation diet, so it probably doesn’t matter.
You will starve to death before any of the ancillary effects kick in.
You may want to skip the excersize
At 1000 calories a day, you have 60 days before you starve.
I am thinking none of the other issues will have manifested before the death kicks in
The OP says exclusively one or the other. While humans do need a little fat, we need a lot more protein. Essential amino acids aren’t micronutrients; they’re macronutrients, and I’d expect essential amino deficiency would kick in quicker than rabbit starvation would.
In any event, the right answer is certainly not carbs. Carbohydrates are great for getting a lot of Calories easily, so if we were talking about equal amounts of effort for each diet, they might be a contender, but we’re not talking equal effort; we’re talking equal amounts of Calories, so the effort doesn’t matter.
Definitely not carbohydrates. When it comes to choosing fat or protein it would depend on your current status. An obese person would do better with the protein and a bodybuilder type better with the fat.
Some thoughts to throw in the mix.
The problem with all protein is that it could poison you, likely within weeks; you’d get hyperammonemic, acidotic and die. A human simply cannot digest that protein load. No protein would kill you eventually too but you’d work through digesting your own skeletal muscles for the essential amino acids first. Maybe 30% of you is skeletal muscle. In a bit you’d to get to organs like heart, so not good, but all protein is the only one that would actively poison you.
Protein also by far takes the most energy to convert into the energy that our cells use. Of those 60,000 calories you’d net only something like 45,000 usable - fewer than for fat or carbs.
Certainly you need some essential fatty acids also but if our OP is a typical Western male then he is something like 30% fat, and more if our OP is female. That’ll provide your EFAs for a while. And if obese then longer.
Both carbs and fats are close in terms of digestive efficiency to into energy usable by cells. Fat maybe a hair more efficient.
OTOH if keeping to a 500 to 600 Cal/d all protein diet the protein load might stay below toxic levels and a good obese Westerner fat store might be enough to support its digestion for a bit.
If protein toxicity can be avoided then the issue is which is would kill you first - overall starvation because of protein’s greater digestive costs, or heart arrhythmia caused by breaking down heart muscle due to lack of essential amino acids?
Can you provide some cites for that? You’re a medico, I know you know what you’re talking about, but a friend says she has “reversed” her type 2 diabetes by switching to a ketogenic diet (e.g. her A1C was 11 at diagnosis, it’s now 5.2; her cholesterol levels have also normalized). I maintain that the disease is still there, it’s just controlled through diet (and she doesn’t disagree) - so the term “reverse” is really wrong; the blood sugar levels are the symptom, not the disease.
From everything I’ve been able to find, one’s A1C does indeed drop - but that’s because there are almost no carbs to be turned into sugar.
I haven’t been able to find anything reputable (aside from personal anecdotes online) saying what it does to your ability to process what carbs you DO ingest. That’s what I’d like to read more about. In other words, if she (keto) and I (just into the T2D range, reduced carbs but NOT eliminating them) each ate a cookie, would her blood sugar spike more than mine?
Back to the original question - simply because I’ve been reading so much about keto (and let me tell you, it’s weird as hell to have a doctor tell me to eat MORE fat :D), I’d vote for “all fat”. Vitamin supplementation might stretch that out for a bit, but sooner or later you’re gonna need at least a little protein.
Oooh - unless you’re subsisting purely on sugars, almost all sources of carbs have at least a LITTLE protein. Are you going on the All Sugar diet or just eating nothing but veggies, fruits and grains? That changes up my answer.
No matter how often this is repeated on every calorie question, humans don’t work that way. We don’t eat because we know we Need 200 calories, having burned that much in the past 4 hours. We eat more calories than we Need, we eat because of a bunch of Feelings, and dozens of factors influence how much we eat, as studies have shown.
The latest study (with a small Group of students) that tackled the “all calories are equal” Statement was:
students were divided into three Groups. Group 1 got “normal” diet, eg. Pasta bolognese. not too healthy, but not too much calories, either.
Group 2 got “rabbit Food” - a big bowl of salad with some Proteins (chicken strips) etc. What nutriotinists, doctors etc. agree on as really very healthy Food.
Group 3 got “fast Food” - burgers and fries.
All meals had been very carefully counted so that they had the full amount of calories necessary for Age, exercise and sex and the same nr of calories for each group, but obviously the Portion sizes were very different. There were 3 meals a day.
After less than one week, the Fast Food Group mutinied. They were hungry all the time, because their Portion was far too small (the same nr. of calories, remember).
So the scientists agreed to give them more, but, in order to still make it comparable, increased the sizes and calories for everybody.
With the new amount, Fast Food was barely full, normal got big portions … and after several days, salad Group mutinied. Why? Because they now had to eat a giant bowl of salad … and were fed up, far too full. Not only did it take them too Long to finish one meal, they still felt full when the next came.
So - not all calories are the same because humans aren’t like cars burning Petrol. As Long as things like the size of the plate you’re eating from influence how much you eat in order to feel full, the taste and Feeling of fullness Play a role.
Obviously not QtM and this recent meta-analysis is not a cite that exactly supports it but the question is a really interesting one and the article may be the best source for the information you are looking for available so far. Not for ketogenic but just the macronutrient balance question anyway.
Bottom line from the cited article is
I think it is hard to tease out how much for any individual is from the macronutrient composition per se versus fat loss. Lose fat mass, reverse some inflammation, and you will reverse some insulin resistance. The meat (so to speak) of that review gets deep into those “diverse effects”.
The OP posited pure carb/fat/protein diets, and that’s what my thinking was based on. I’m not going to try to compare a protein only (or fat only) carb-free diet to a low carb one. As DSeid points out, the devil is in the ‘diverse effects’. 