March 15, 2011 4:26 PM   Subscribe

Will having a large percentage of my caloric intake come from fruit lead to more problems than health benefits?

For the past three weeks or so, I've switched my diet up to consist solely of fruits, vegetables, protein shakes (only the powder and water), and seldom some meat. The importance here is that a large portion of my calories come from fruit; probably ~70% of my daily caloric intake. The main fear for me is that the acidic and fructose-y nature of the food will cause my teeth to become messed up (mainly from the oranges and apples). So far, my difference in energy levels has been noticeable, and I would like to continue eating this way. I haven't dealt with digestion problems or any immediate issues - I'm just wondering if eating this way in the long term will cause me more harm than good.
posted by Evernix to Health & Fitness (26 answers total) 2 users marked this as a favorite
Doesn't sound like a good idea to me. You're living largely on sugar. Fat is an essential nutrient -- your body requires essential fatty acids to function properly. You may be missing out on other necessary micronutrients as well. A balanced, varied diet with more fat and protein (from whole food sources) is a better plan.
posted by Anatoly Pisarenko at 4:35 PM on March 15, 2011 [2 favorites]

Having a large percentage of your caloric intake coming from one type of food, any type of food, is always going to cause problems in the long term. Fruit are pretty homogeneous so there are a lot of types of nutrients you're missing out on (complex carbohydrates, fats, and many minerals come to mind immediately). The whole balanced diet thing isn't some old fashioned fad, humans really are designed to eat a variety of foods.
posted by shelleycat at 4:40 PM on March 15, 2011

I totally agree with those comments above. The thing with fruit is that with that much sugar you'll have a little burst of energy and higher metabolism for a bit but after a while you'll be overloaded and will gain weight and might even become pre-diabetic.

It almost sounds like you're making awesome fruity smoothies. Whether you are or not, replace a good portion of that fruit with yogurt or light cheeses and compliment it with nuts and grains.

That's what I did. Advice channeled through me from my awesome M.D.
posted by snsranch at 4:50 PM on March 15, 2011

There's nothing concrete yet, but I've been reading some unsettling things about fructose. People may be surprised about how UNhealthy it is if things pan out.

Avoid, avoid.
posted by unixrat at 5:15 PM on March 15, 2011

I haven't read the bad things about fructose but I wouldn't be surprised if they are out there, given how much bad news I've heard about sucrose or whatever refined sugar is. It was my understanding that part of the reason fruits aren't as bad as say, candy bars, is that fruits balance the fructose by also providing fiber. Which makes sense; sugar cane is very fibrous to my understanding. I suppose this would be another point in favor of trying to balance out fruits with vegetables.

Right now I'm working on eliminating refined sugar from my diet, and fruits end up being a large part of my diet. I mostly have this part down, so I'm now working on adding those dark green leaves to the mix. I know that in my case, my body really actually is noticeably more healthy when I'm getting my greens.

I like to add olive oil to EVERYTHING. It gives me the fat that I don't get from the 25-pound bags of oranges I buy. Oranges? Not a solid snack. Oranges plus olive oil and maybe a dark green leaf or two? Yes. Add your favorite spice if you want some extra pizzazz. Yes. Cheeses, olive oil, nuts, yogurt, beans, pea/nut butters, avocados, etc., will all go well with your fruits. And they're tastier than protein mixes, in my opinion. I don't know anything about nutrition beyond what I as a layman have read, but I wouldn't be surprised if whole foods are typically better for you and tastier than protein shakes, but they might be more work to eat.

Oh oh oh! one thing maybe you could do is throw some kale or chard or spinach or whatnot in right at the end of the blend cycle! I did that with a persimmon/halfandhalf/blueberry/chocolatepowder/kale shake and damn, it was good. You probably don't get the same fiber you would if it wasn't blended, but at least you would be getting whatever nutrients come from greenery!

Another point is that if you are eating things based on what is in season , you might be getting a balance of nutrients over the course of, say, a year. For instance, according to my "history of environment in the middle east" teacher, people can live on dates and milk for half a year at a time and make up for it the other half the year when they harvest food from oases!

Dates are packed with all sorts of vitamins and minerals; oranges and apples and protein shakes may be roughly equivalent, but personally I would be wary. Protein shakes are based on an ideal person, not my own personal needs - I think that dietary needs are more individualized than a manufactured shake can really account for.

Tl;dr: keep listening to your body. Everything in moderation, including moderation.
posted by aniola at 5:32 PM on March 15, 2011

One way to address the fat deficiency mentioned above is to add things like nuts to your diet. Also, avocados. (mmmm, avocados...) Also, with regard to missing out on micronutrients, I think your best bet is to keep up a variety of foods - but that doesn't necessarily mean branching out too far from what you're currently doing. Eat a lot of different types of fruits and vegetables. I mean, there's really lots of them. If you're just eating 1500 calories worth of apples, oranges, and bananas a day then, yeah, you might have problems - just like if you were eating 1500 calories of yogurt or chicken or rice each day.
So keep eating the fruits and veggies, just make sure that this includes things like olives, blueberries, peppers, celery, raspberries, guava, broccoli, cucumbers, spinach, blackberries, eggplant, cauliflower, carrots, kiwi, strawberries, plums, pineapples, rhubarb, mushrooms, cabbage, and, among other things, avocados. And also don't forget to include the nuts or some other source of sufficient protein.
posted by Quizicalcoatl at 6:07 PM on March 15, 2011

If you'd like to learn more on fructose, this presentation by Dr. Robert Lustig is very informative.

I personally try to limit fructose to 25g a day for the reasons presented in the video, as well as others - it is much more fattening than other forms of sugar, even with equal calories. It may have to do with the fact that fructose does not satiate, whereas glucose does.

While sometimes foods in their natural state are less damaging than their deconstructed nutrients would indicate, I play it safe and limit fruit. (Any non-vegetable-oil fat is fair game!)
posted by Earl the Polliwog at 6:08 PM on March 15, 2011 [1 favorite]

Oh, and just for reference - glucose and fructose are the two most common monosaccharides, or simple sugars. Other sugars, like sucrose, are made up from these and other simple sugars. Sucrose is a pair of each; high-fructose corn syrup is usually a mixture of 55-60% fructose and 40-44% glucose. Agave nectar is much higher, near 90% fructose, so it should be avoided.
posted by Earl the Polliwog at 6:11 PM on March 15, 2011

Doesn't sound too healthy to me, but this guy does it: the fruitarian.
posted by sabh at 6:21 PM on March 15, 2011

it is much more fattening than other forms of sugar, even with equal calories. It may have to do with the fact that fructose does not satiate, whereas glucose does.

That doesn't make sense. Lack of satiety is a problem because then you eat more. Eating more does not mean "equal calories". Fructose is the new fat, it's trendy to be scared of it at the moment.

Eating really correctly can be kind of difficult as there's a lot of bad information around, plus aniola is on the button with diet being individualised. Our genetic differences make us react differently to food and this isn't yet well understood. There really is no one size fits all way to eat perfectly and fads that vilify or lionise one specific food type should always be viewed with extreme caution.

However, it is relatively easy to eat badly and getting >70% of your caloric intake from one limited food group is pretty much a no-brainer for long term trouble. You don't need to drop the fruit, just mix it up and cover all the food groups.
posted by shelleycat at 6:42 PM on March 15, 2011 [1 favorite]

I did this for a while--fruit, meat, and also nuts. I seriously fucked myself up. I started having panic attacks, weakness, and I lost a lot of weight before I realized what was happening, although some of that could have been confounded by additional health issues.

Nuts have poly, mono, and saturated fat, but not enough mono and saturated. Poly goes right through you, and doesn't seem to produce the satiety that the other kinds of fats do. Ancient man could not pound down nuts like we can because they had to get the shell off.

Unless you are eating really, really fatty meat (which you are not with just the protein shake), do not do this. Adding olive oil to everything helps. But you really need a source of lots of saturated fat like milk, cheese, tallow, or lard. And/or brisket or something.

Fat is not just fuel; it is also a building block. You can't leave it out.
posted by zeek321 at 6:49 PM on March 15, 2011

shelleycat, it is because it resulted in those people eating more calories from other foods, and/or expending less energy. The amounts of fructose and glucose given to the study subjects were the same and thus the amounts of calories from the sugars were equal.

There is a lot more to fat gain and loss than "calories in - calories out = fat gain, so eat fewer calories". Both sides of this equation are flexible and not necessarily under our direct control. See Taubes' "Good Calories, Bad Calories" for more on this.
posted by Earl the Polliwog at 6:57 PM on March 15, 2011

High fructose intake (including fructose intake from fruit) is linked to high triglycerides and LDL cholesterol, hypertension (high blood pressure), gout, insulin resistance, impaired glucose tolerance, and fatty liver disease.

You are not eating any fat. The human body cannot make essential fatty acids, and must get them from food — that's what makes them essential. Additionally, several vitamins (A, D, E, K) and other nutrients are fat-soluble. They cannot be absorbed or used in the body without a source of fat. The body derives almost none of the fat-soluble nutrients in raw or cooked vegetables and fruits if they are eaten without any fat.

Is there a specific reason you are getting almost all of your protein from an industrially manufactured isolate or concentrate?

If you like the way eating a fruit-and-vegetable-heavy, water-heavy diet makes you feel, shift a bulk of your diet to lower-sugar vegetables and a reasonable amount of fruit. Include fatty foods, especially with your vegetables and fruits. Eat foods containing protein (protein powder is okay in moderation; nuts are rich in fat but not very high in protein). Keep most of your food in a form you have to chew.

We haven't identified all of the useful compounds in foods. We also don't know how all of the compounds found in a single food, or in a group of foods commonly eaten together, affect the body's handling of all of the other compounds in the food or foods. That means you generally don't want to rely on any one single item in isolation as your dietary source of something the body needs, especially if it's a food-like product lacking the co-factors found in the original food.

(For more popular criticism of nutritionism, start with this 2007 piece by Michael "Don't eat anything your great-great-grandmother wouldn’t recognize as food"Pollan.)
posted by hat at 7:00 PM on March 15, 2011 [2 favorites]

Crud, I'd meant to throw in this link to the last post. It's about how even if you give mice (and presumably humans) fewer calories, weight loss is not guaranteed.
posted by Earl the Polliwog at 7:01 PM on March 15, 2011 [1 favorite]

You need fat in your diet to absorb vitamins A, D, E, and K, all of which are essential for a healthy body. Like others above, I would recommend adding more variety to your diet, particularly some source of fat.
posted by vytae at 7:02 PM on March 15, 2011

About dental health. The main thing to be concerned about with the surface effects of high-acid or high-carbohydrate foods is how long they're in contact with your teeth and the rest of your mouth.

Starchy foods and sticky foods like crackers, cookies, breads, potatoes, dried fruit adhere to the teeth for a while and support bacterial growth. Similarly, eating high-sugar or high-acid foods frequently or sipping acidic drinks like smoothies, juices, sodas over long periods of time keeps your mouth bathed in sugar or acid, which damages enamel and feeds bacteria.

You can protect your teeth by rinsing your mouth with water immediately after you eat, brushing/flossing your teeth 30 minutes after the meal, and not drinking acidic things or eating between meals.
posted by hat at 7:29 PM on March 15, 2011 [2 favorites]

Hat just gave the same spiel the dental hygienist gave me last time I was there, and the hygienist had been at it for 20 years.
posted by aniola at 7:45 PM on March 15, 2011

Don't sweat it
posted by tiburon at 7:49 PM on March 15, 2011

Heads-up: Lustig's "fructose toxicity" theory has been hotly contested by other nutritionists. I certainly can't speak for it's merit either way, but it warrants investigation. A quick Google search turns up this summary/analysis as a second hit, for example.

Good luck! Truthfully, your diet doesn't strike me as particularly extreme or irregular, provided your fruit consumption is balanced with vegetable, complex carbohydrate, and protein, perhaps in a 1:1 ratio.
posted by alexandermatheson at 10:16 PM on March 15, 2011

shelleycat, it is because it resulted in those people eating more calories from other foods, and/or expending less energy. The amounts of fructose and glucose given to the study subjects were the same and thus the amounts of calories from the sugars were equal.

Which still doesn't mean fructose itself is more fattening, its the other food that's causing weight gain. Maybe your summary is bad but it's all coming across as pretty confused to me. I know all about calories in/calories out and whatever, I've just finished a PhD in a nutrition-related field. Taube has some good points but also many flaws (there are several articles around going through his stuff), and I stand by my assertion that hating fructose is a fad right now. Sadly it's just one of many that will come and go.

There's still a lot to be learnt in this area, which is why it can be difficult to get good information. That information doesn't really fully exist yet (and much of the current stuff completely ignores the differences in individual metabolism). None of it means that you shouldn't eat a balanced diet though, which this much fruit isn't.
posted by shelleycat at 10:54 PM on March 15, 2011

If you'd like to learn more on fructose, this presentation by Dr. Robert Lustig is very informative.

It is, but also read this counterpoint to get a more balanced view.

See Taubes' "Good Calories, Bad Calories" for more on this.
But then again, also read his critics, for example here and the links in this post.

I agree with others that a bit more fat and protein would probably be better, and I would place more emphasis on vegetables (mainly for the minerals that are not plentiful in fruits). I would put a normal day of eating in an online nutrition calculator and then adjust my diet.

The concern for your teeth is also warranted. Liquid fruit is much worse for your teeth than whole fruit. It matters if you eat all day or if you limit yourself to about 5 meals a day. It also helps to end your meal with something that is neutral for your teeth, like nuts (or xylitol gum/mints if that's acceptable for you).
posted by davar at 3:17 AM on March 16, 2011

Response by poster: Thanks, all. For clarification, I never had any fruit smoothies. Only protein powder smoothies. But anyway, thanks a bunch for all of this information. I'm a pretty athletic person and I believe having a healthy, physically fit body in combination with a positive mindset is key to becoming more involved with the world around me. Alot of "fitness" enthusiasts become engrossed in confirmation bias in terms of what's "healthy" and just roll with it. My views on fitness and health change frequently, and I'm always welcome to new information and findings. So, again, I thank all of you for your time.
posted by Evernix at 6:33 AM on March 16, 2011

Fruit isn't fructose. Fruit is fructose and fibre.

This matters.
posted by flabdablet at 8:20 AM on March 16, 2011 [1 favorite]

I have eaten a very fruit heavy diet with little fat and protein for 6-months and I have been less sick and feeling more well than ever. There's a community of fruiteaters online and

I do think that the modern idea of nutritional balance are more grounded in tradition, availability and economical interests than in science and that you can consume much less protein and fat than is commonly believed without drawbacks, at least when you are adult. We did evolve on the African savanna to a large extent and apes are our closest evolutionary relatives after all. I do not suggest excluding fat and protein from the diet but I do not believe you need to worry about it. I do recognize that there's little to none science on semi-frutarianism, but many benefits of fruits are well document and I think the nutritional reasoning for eating un-cooked whole food in an as large extent possible is convincing.
posted by okokok at 8:22 AM on March 16, 2011

I would like to add that I also consume a lot, and I mean a lot, of fresh vegetables and salad.
posted by okokok at 8:32 AM on March 16, 2011

Anecdata: I have a friend whose dentist has specifically called her out about her apple and orange habit (she juices daily in addition to eating the fruit itself). She didn't mention it or ask him about it - he could tell by looking at her teeth.
posted by perpetual lurker at 10:28 PM on March 17, 2011

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