I know a bit about calories and and nutrition and such, but one question came across my mind recently: To our bodies, does it matter how much a food weighs or how dense it is?
If I can satisfy my daily energy and nutritional requirements via soda and multivitamins, do I still need to eat solid food? Conversely, would I be able to eat pounds and pounds of salad (with nearly no calories) and survive off that?
Or, given the choice between two items with similar nutritional benefits, calorie contents, and ingredients – e.g. a cracker versus a slice of bread – does their weight or density matter?
I can’t believe I don’t know this :eek: It just seems counter-intuitive, for example, that a tiny little cup of syrup can provide more energy than an entire loaf of bread that weighs so much more.
The soda and vitamin pills wouldn’t give you any fiber. You wouldn’t so much get constipation as have nothing to go for.
The lettuce would be almost-exclusively fiber: no vitamins, minerals, proteins.
A complete and equilibrated diet includes things like fiber for which there are no “recommended daily requirements”. Also, complex carbs (like you get in not-overcooked pasta and rice) take up more volume than an equivalent amount of table sugar and are healthier because they get processed more slowly.
Aside from vitamins, minerals, and essential fatty acids (in small quantities), you need carbohydrates, proteins, and fats. The only thing you’re going to get from soda are simple sugars (that is, carbohydrates). These give you quick, easily accessable energy, but don’t give you fundamental organic building blocks (proteins, many of which your body can’t synthesize) and the high energy density fats which help dissolve and store many vitamins until needed. (Your body can, of course, synthesize body fat, but this will not contain all nutrients and specifically not the essential fatty acids). The result; you’ll have spiky blood sugar and insulin levels, but no means of rebuilding tissue lost in normal catabolitic processes. You also need proteins and fats to absorb vitamin supplements, so just because you pop a multivitamin supplement with 100% of recommended dietary vitamins doesn’t mean that you’re actually getting use of all of it, especially if your diet isn’t otherwise balanced, and in fact there’s considerable debate as to how much many vitamin supplements actually help you at all.
As **Stranger On A Train ** pointed out, there’s more to meeting your body’s “nutritional requirements” than the raw calorie and vitamin/mineral content of your intake. It also has to be in a form that your body can use.
If you wanted to achieve complete nutrition without “food” as we usually think of it, a better option would be the total parenteral nutrition, i.e., infusing a nutrient solution directly into your bloodstream. This kept my father alive and nourished for several weeks while he recovered from complications following abdominal surgery.
However, the daily volume of TPN probably isn’t necessarily smaller than that of the food you’d ordinarily eat. Ryan Heinrick’s TPN calculator comes up with about 2 litres’ worth of solutions for a male requiring only 2000 calories/day. If you’re fairly active, you’d require more.
IANAD; surely a medical Doper will be along to speak with authority on the topic.
I think that the reply that **Reply ** is looking for is more along the lines of any of those “meal replacements” out there, be them shakes or bars. They are supposed to give you about a third of your daily requirements of (most) everything (according to their labels). Could you really live on three of those a day?
You certainly could for a while. I think you’d suffer from fat starvation after a while, but given a sufficient calorie intake of proteins and carbohydrates, plus required essetial fats, vitamins, and minerals from supplements (assuming that you do absorb and utilize these) it would be quite a while; months, likely, before deleterious effects are manifest, especially if you already have a typical double-digit reserve of body fat.
I know you’re not asking about weight loss, but your comment about a cracker vs. a slice of bread reminds me of what Weight Watchers has to say about “energy density”:
<<What is Energy Density?
You know a cup of ice cream has more calories than a cup of broccoli. That, in a nutshell, is energy density – the number of calories in a given volume of food. Foods with a high-volume/low-calorie ratio are low-density foods. So for example, most vegetables have a low energy density; most high-fat desserts or fried foods have a high energy density.
Why is the Energy Density of a Food Significant?
Why not just count the calories? Because foods that have a low energy density will be more satisfying, and you will feel fuller after meals. And if you eat more of the foods that have a low energy density, you’ll still be able to enjoy the occasional treat in moderation. Filling your daily diet with low-energy-density foods increases eating satisfaction with fewer calories because these foods are usually higher in water content, lower in fat, and in some cases, higher in fiber.>>
So for example, for folks trying to cut back, they encourage grapes instead of raisins.
The problem isn’t really what we take in, but what we spend. I don’t have a cite for this, as I got it from a lecture, but it makes sense to me, so make of it whatever you will.
The average female office worker will spend about 1800 calories a day. Spreading that over three meals means 600 cals per meal and there is no way to have a full satisfying meal, containing all the nutritions you need (vitamins, minerals, fibres, EFA) on that little food. If in fact you’re only eating 1800 cals a day, using regular food, you have malnutrition. Those proteins, carbs and veggies will not give you enough to stay healthy.
Essentially, the guy said that the “cure” to obesity is not eating less (because we eat what we need to, to survive), but spending more, to ballance our intake.
My aunt did, for the last few months of her life in the nursing home. But she wasn’t getting hardly any exercise at all, just laying in bed or sitting in a wheelchair all the time.
And the nurses were concerned about this, and constantly trying to tempt her to eat some of the regular food. They didn’t seem to consider those as adequate for a complete diet.
Thank you all! That was informative, especially the parts about proteins, carbs, fats and “energy density”. I guess what I was really trying to ask was, “What does solid/regular food offer that nutrition supplements and vitamins don’t?”
Let me paraphrase to see if I understand you guys correctly:
Solid food with low energy density gives you the feeling of fullness, but not necessarily any more or less nutrition than supplements. Supplements/shakes and TPN, on the other hand, can provide all the nutrients that your body needs, but won’t make you feel full?
Vitamins and calories aren’t enough because we also need proteins, fats, and carbohydrates. Real food and meal replacements shakes can provide these, while soda & vitamins can’t (except the carbs).
