Let us begin our examination of the paradox with a table that shows the quantity of each food or food type needed by itself (i.e., a mono-diet of one food or type of food) to provide 2,000 calories per day. Please note that this is for comparison purposes only; it is not suggested that you try to live on only one food, or food category.

Daily Food Quantities Needed (in a Mono-Diet)
to Provide 2,000 Calories

Note: calories below are for raw foods, except where indicated.

Let's now review and evaluate the data in the table.

Vegetables only--the "gorilla diet"

Massive bulk of food required. Eating vegetables and greens only could be called the gorilla diet, because (mountain) gorillas are folivores and eat a diet that is predominantly leaves and vegetative matter, although they also eat smaller amounts of fruits, roots, and insects. (Note: gorillas are not vegans--they deliberately eat insects, if a modest amount.) Lowland gorillas are foli-frugivores and eat more fruit, and more insects, than mountain gorillas. If you try to live on only raw vegetables, you will need to eat 20 pounds (9.1 kg) per day, just to satisfy your calorie requirements. That's a lot of food to eat each day! Consider the time required to eat (and excrete) so much food on a daily basis. Indeed, you would be forced to lead a life parallel to that of the gorilla--a life that consists primarily of eating, excreting, and sleeping. (It's no coincidence that many raw-foodists seem to be primarily focused on the topic of food and eating it for much of their day.)

The human body is not that of a folivore, although we do have some (limited) adaptations for it. The noted comparative anatomy expert, D.J. Chivers, reports that the human gut (digestive system) is that of a faunivore (meat-eater) with some of the adaptations of a folivore. (References: Cambridge Encyclopedia of Human Evolution, 1992, Cambridge University Press, pp. 61, 64; see also D.J. Chivers and P.J. Langer, The Digestive System in Mammals: Food, Form, and Function, 1994, Cambridge University Press, p. 4.) In other words, we have the mixed set of adaptations of an omnivore/faunivore, so although we are not purely or primarily folivores, we can certainly eat raw vegetables. [Note: Chivers uses a slightly different definition of the term "omnivore," and suggests instead that the human gut should be described as that of a faunivore, rather than omnivore.]

Diuretic effect of common green vegetables. A diet of exclusively raw vegetables provides challenges over and above the volume problem. Many common vegetables are diuretic: asparagus, celery, dandelion greens, fennel bulb, onion, parsnip, and parsley. (References: The Encyclopedia of Herbs and Herbalism, ed. Malcolm Stuart, 1981, Crescent Books, pp. 148, 154, 161, 235-236, 270-271. Also see The Complete Medicinal Herbal, by Penelope Ody, 1993, Dorling Kindersley, pp. 37, 59, 103.) The ultimate result of a diet high in diuretics can be chronic dehydration--which can cause serious problems in and of itself. This comment also applies to vegetable juices, specifically green juices (which usually have a celery juice base and/or include other diuretics).

Side note: The reference above by Penelope Ody reports that many sweet fruits are diuretic: oranges (p. 49), strawberries (p. 60), apples (p. 77), raspberry (p. 93). Those readers who have followed diets high in sweet fruits have probably experienced the excess urination so common on such diets. This leads us directly to the next topic...

100% sweet fruit diets-- are you sure that you are getting enough sugar? :-)

From the table, we see that one needs to eat 6.7-9.3 pounds (3.0-4.2 kg) of fruit daily to satisfy calorie requirements. Further, the 9.3 pound (4.2 kg) figure is for the "4 sweet fruit" blend, on a net (edible portion only) basis. Assuming an average waste factor (peels, inedible seeds, cores) of 28.5% (per USDA Handbook--see Appendix 2), we divide the net fruit consumption estimates by 0.715, to find that one needs to eat 9.3-13 pounds (4.2-5.9 kg) of whole fruit per day to get the required net weight. That's a lot of fruit to eat!

Further, the "4 sweet fruit" blend is slightly over 10% carbohydrate by weight, nearly all of which is sugar. Applying this to the weight of fruit required indicates that one would be eating ~0.67-0.926 pounds (300-420 gm) of sugar each day. Needless to say, that explains why many fruitarians experience the symptoms of excess sugar consumption (frequent urination and thirst, fatigue, sugar highs/blues, etc.). Also, it seems reasonable to regard a diet in which sugar is the overwhelmingly predominant calorie source (little fat, starch, or protein) as a form of "sugar addiction."

Fruit-juice diets are not a long-term solution

The table shows that fruit juices are high in calories and are a concentrated food: you can satisfy your calorie requirements with 3.7 quarts (3.5 liters) of juice. On the surface, it appears that juices are a solution to the calorie paradox. However, consuming this amount of juice would give you a very large dose--approximately 1.066 pounds (0.483 kg)--of sugar each day. Such a large quantity of sugar may cause negative side-effects, particularly in the long run.

Some fruitarian "experts" argue that you should juice your food, to avoid the calorie paradox. While juices are natural, there is much to consider before basing one's diet on fruit juices. Note that:

• Chimps practice a crude form of juicing, called wadging. (This means that a food may be crushed with their palate, the juices sucked out, and the leftover pulp spit out.) However, this constitutes a very small portion of their food intake; their diet also includes whole fruit supplemented by leaves (the two largest components), and insects, meat, and other foods (which make up the remainder). Extremists like to point out that other animals generally don't cook their food. Can the fruit-juice diet advocates name (and document) even one wild primate that lives on a diet that is predominantly fruit juice (juice specifically, and not the fruit flesh--some primates are frugivores)?

• Juices are fractionated foods. Juices are natural in that they are extracted from whole foods. They are, however, fractionated (partial) foods--something that raw-food advocates normally argue against on general naturalism principles. Juices lack fiber, and one major blender manufacturer reports that the pulp left over from juicing is more nutritious than juice.

• Electric juicers are UNnatural. Electric juicers, required if one is to consume large amounts of juice, are no more natural than electric stoves. Extremists like to say that you were not born with a stove on your back. This is true, and you were not born with a juicer on your back (or in your mouth), either! :-) (Note: Of course, the human mouth can juice soft fruits, but it is slow and inefficient. Also, extensive contact with fruit acid is known to erode tooth enamel.)

• Very few rawists live on fruit juices alone, or even diets in which fruit juices are predominant. There are very few, if any, credible success examples for long-term (5+ years) fruit-juice diets.

• Sweet fruit juice may cause sugar/insulin spikes. Juices are more rapidly absorbed by the body than whole foods. Sweet fruit juices are very high in sugar (~1.05 pounds of sugar per day, per the table). It is very easy to drink juices (too) quickly, especially sweet fruit juices. The result of this is that sweet fruit juices may produce sugar highs and insulin spikes that are more extreme than the reaction caused by eating whole fruits. (See The Diabetic's Total Health Book, by June Biermann and Barbara Toohey, 1992, Jeremy P. Tarcher/Perigee Books, pp. 88-89.) Your pancreas and liver may be able to handle this in the short run, but are such extremes good for you, multiple times a day, over the long run?

• Effects of fruit juices aggravate the hunger, craving, and bingeing problems already present in fruitarian diets. Besides causing "sugar shock" when consumed in excess, fruit-juice diets are not satisfying. You drink juices and you are hungry a short time later. Fruitarianism is notorious for cravings and binge-eating; trying to live on an exclusive diet of rapidly absorbed, high-sugar fruit juices will only make the problem worse.

• A diet of only fruit juices may be deficient in protein, even if one uses the low-protein requirements advocated by those promoting crank science theories that allege to "prove" protein is "toxic," in the sense that the metabolic by-products of protein digestion are allegedly harmful. (Such theories are based on an irrational, pathological fear of "toxins" and an amazing ignorance of the reality that the human body is well-equipped to dispose of the metabolic by-products of protein digestion. See: "Is Protein Toxic?" [not yet available] for an in-depth examination of the various nonsensical but influential theories--in fruitarianism/rawism--about protein.)

  To date, such theories are usually based on the protein content of whole fruit, not juices. The protein content of fruit juice may--or may not--compare to that of the underlying fruit (nutritional analysis data are necessary to establish this point). Note that protein deficiencies are rare or non-existent, even in fruitarian diets. Three possible explanations: (1) the body can adapt to low-protein diets within limits, (2) those on fruit juice diets (over-) consume large volumes of juice and get adequate protein anyway (along with plenty of that important nutrient, sugar! :-) ), or (3) the fruit-juice diet advocates get their protein via cheating and binge-eating. My opinion: the latter, #3, is the most plausible explanation.

To summarize: Fruit-juice diets are theoretical, not practical, and are not an effective long-term solution to the calorie paradox. Also, please note that juices can be and are used in therapeutic diets, and can be consumed in moderation as part of a diverse diet. I do not wish to demonize fruit juices (or any other food) here. Used properly, juices (including fruit juices) can promote health; but trying to live on a diet that is predominantly sweet fruit juices is not a good idea.

Dried fruit--concentrated sugar

The table shows that dried fruits are a concentrated food: only 1.71 pounds (0.78 kg) will supply daily caloric requirements. Because they are high in sugar, this amount of dried fruit will provide ~1.1 pounds (0.5 kg) of sugar. Once again, the sweet fruit diet--whether fresh, juiced, or dried--has sugar as the primary calorie source.

Trying to live on a diet of only dried fruit is not a good idea. Dried fruits are notorious for causing flatulence. The concentrated sugar may, in some individuals, promote or aggravate reflux--digestive acids coming up out of the stomach. Dr. Stanley Bass, as cited in Survival into the 21st Century, by Viktoras Kulvinskas, reports that consumption of dried fruit may aggravate hemorrhoids as well. (Note that the Survival... book is, in some sections, a compilation of fruitarian folklore. It's interesting that a book that glorifies fruitarianism also mentions some of the potential problems of the diet.) So, dried fruit as an occasional treat may be okay for some people, but making it the center of your diet is a bad idea.

• Cucumbers. To get the caloric value equivalent to one pound (or kg) of sweet fruit, one needs to eat 4-5 pounds (1.8-2.3 kg) of cucumbers. Substituting cucumbers or tomatoes for sweet fruit will cause substantial weight loss, unless one eats a MUCH larger amount of cucumbers or tomatoes to get the same number of calories. Many people find that cucumbers are a "heavy" food, and it is very difficult to eat as little as 2.2 pounds (1 kg). Hence, the idea of consuming 33.9 pounds (15.4 kg) in one day is ludicrous. Further, reliance on cucumbers as the predominant food in one's diet may promote (the equivalent of) anorexia nervosa in the long run (some anorectics live on a diet of cucumbers and celery).

• Tomatoes are not much better than cucumbers. One would need 23.2 pounds (10.5 kg) per day to satisfy calorie requirements. Additionally, many people are sensitive to raw tomatoes and cannot eat them in quantity without negative (and unpleasant) reactions. Tomatoes are generally acidic, and 23.2 pounds (10.5 kg) of even the low-acid varieties might supply excess acid.

• Most neutral fruits are very low in calories, and it is hard to eat them in quantity, as they can be coarse, heavy, not very appetizing, and/or cause side-effects.

• Zucchini (courgette) provides only 14 cal/100 gm = 63.5 cal/pound; eggplants (aubergine) are 26 cal/100 gm = ~118 cal/pound; yellow summer crookneck squash are 19 cal/100 gm = ~86 cal/pound; okra is 38 cal/100 gm = ~172 calories/pound.

• Sweet peppers (25 cal/100 gm = 113.4 cal/pound) are a popular neutral fruit; however, raw sweet peppers are notorious for causing gas--both stomach gas (belching) and flatulence. Basing your diet on sweet peppers (and/or other neutral fruits) would be very difficult indeed.

• Some fruitarian "experts" can't tell the difference between a neutral fruit and an acid fruit. Classified as neutral by some fruitarian proponents are the following acid fruits: lemons (29 cal/100 gm = 131.5 cal/pound), limes (30 cal/100 gm = 136 cal/pound), cranberries (49 cal/100 gm = ~222 cal/pound). However, a warning applies here again, which the fruit advocates often don't bother to tell you: consuming large amounts of acid fruits may cause serious damage to your tooth enamel. It's unfortunate when so-called "experts" can't tell the difference between acid and neutral fruits, and fail to warn readers of the risks of consumption of large amounts of acid fruits.

• Sweet corn (86 cal/100 gm = ~390 cal/pound) is another food that may be classified as a neutral fruit by some. However, sweet corn is 19.02% carbohydrate, including substantial sugar, and a more appropriate classification for sweet corn is in the sweet fruit category. (Modern hybrid sweet corn can be very high in sugar.)

• Some fruitarian "experts" don't distinguish between a juicy neutral fruit and an oily fruit, and may classify avocado and olives as neutral fruits. However, under the scheme used in this paper, avocados (and olives) are considered to be fatty fruits.

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