Whole, ripe, unprocessed, raw fruit is full of fiber, pure water, vitamins, minerals, and other micronutrients that are essential to health and which are missing in refined carbohydrates. The main macronutrient derived from digested fruit is glucose, a simple carbohydrate or sugar that, along with fat, supplies important energy to the human body. All starch food must be digested to glucose before it can be used by the body for energy, so it makes sense to make fruit a significant source of carbohydrates in your diet.

When people first discover the health value of eating fruit they may be inclined to mentally associate extreme amounts of fruit intake with health. For example, Dr. Stanley S. Bass described how he went on an orange-juice diet to recover from ailments as a young man. The benefits he received from the large amount of orange juice he consumed helped put his body into a better nutritional balance after a lifetime of unhealthy eating. However, an unfortunate outcome of this early experience is that it seems to have led Dr. Bass to mentally associate large amounts of fruit intake with health. This eventually led to more excessive fruit intake, which eventually led to more health problems, such as missing teeth! Dr. Bass then conducted a series of dietary experiments on mice and came to a startling conclusion that finally broke his mental association between excessive fruit intake and health: A diet containing the proper balance of nutrients, including the proper amount of carbohydrates, fat, protein, vitamins, minerals, and other factors is essential for health!

In his book that advocates consuming 80% of calories from mostly fruit, The 80-10-10 Diet, Doug Graham states, "Ask a dentist what percentage of his or her patients have problems with their teeth because they ate too much fruit. The percentage will be so low as to approach zero" (p. 47–48). This misleading statement hides the fact that the average person in the U.S. barely eats more than one serving of fruit a day. In a 2005 Bulletin of the World Health Organization titled The role of diet and nutrition in the etiology and prevention of oral diseases, Moynihan described epidemiological and animal studies that showed fruit is non-cariogenic (doesn't form cavities) when normally consumed, but is cariogenic in excessive amounts. Workers who pick apples and grapes and consume large quantities of these fruits have above average levels of missing teeth. Williams et al., in a 1997 study called Regulation of osteoclastic bone resorption by glucose, found that bone losses occur when blood glucose levels rise above normal. 

Shelton wrote how laboratory experiments have shown normal teeth can be submerged in sugar and acid indefinitely without decay. Shelton's point is that damage to teeth from excess sugar does not begin from outside as much as from within. Excess carbohydrates in unbalanced, high-carbohydrate diets cause disturbances in calcium metabolism that begins the systemic portion of the tooth-decay process (the important part dentists and patients ignore), which eventually leads to surface tooth decay and root problems (the part dentists and patients notice). Excess glucose injected into laboratory animals causes cavities without ever coming in direct external contact with the animals' teeth.

Although natural, unrefined carbohydrates contribute valuable nutrients to a diet along with glucose, the amount of these nutrients is insufficient to prevent body tissue damage that occurs from carbohydrates when consumed in excess. Most of the energy used by the body at rest is from oxidized fat, about 70%. A much smaller amount of  glucose is also normally oxidized in the body to produce energy, water, and carbon-dioxide, which are harmless substances. But an excessive amount of glucose is not oxidized properly, and is burned anaerobically to produce large amounts of lactic acid, pyruvic acid, and advanced glycation end products (AGEs) which tend to lower pH levels, disturb calcium and bone metabolism, and have been associated with cancer cell growth and other diseases.

Excessive intake of fruit and carbohydrates like grains and legumes as well as high-protein nuts also provides too much phosphorus to the body, which also disturbs calcium metabolism and causes bone disorders. Eating very large amounts of green vegetables to supply calcium does not eliminate the damage from excess phosphorus and excess glucose! The best solution is to keep phosphorus and glucose intake under control with a balanced diet. The Reference Dietary Intake (RDI) for phosphorus is 700 mg a day. For more information on phosphorus and bone health, see: How Dairy Products Cause Osteoporosis. 

But isn't fruit an alkaline-forming food? Nutritional concepts such as Potential Renal Acid Load (PRAL) are used to sum and compare the amount of alkaline-forming elements and acid-forming elements in a food to determine which type of element predominates. Unfortunately, even though fruit is predominately composed of alkaline-forming elements, the formula for PRAL ignores the independent relationship between calcium and phosphorus. Shelton wisely warned of this problem in classifying almonds as an alkaline food. He pointed out that almonds contain very high amounts of phosphorus, an acid-forming element. The alkaline elements do not balance out disturbances in calcium and bone metabolism caused by high phosphorus levels, which applies to all food, including fruit. 

If careful attention is not given to the composition of a high-calorie fruit diet, problems can quickly develop as phosphorus levels rise. For example, a 2500-calorie diet made up exclusively of oranges provides almost 1100 mg of phosphorus, which is 57% higher than the RDI of 700 mg. A 1800-calorie diet of tomatoes provides 2700 mg phosphorus! On the other hand a 2500-calorie diet of apples provides only 480 mg of phosphorus, although it is low in calcium. These foods should not be eaten in excessive amounts and need to be properly balanced with raw leafy green vegetables.  

In Superior Nutrition, Shelton wrote, "Most fruits are deficient in calcium, most green leaves contain an abundance of calcium. Nobody lives on fruit alone, so the calcium deficiency of fruits is supplemented by the calcium richness of green leaves." Shelton also wrote in Orthotrophy, "Green leaves are indispensable to the biologic diet. Fruits will not take their places." To help ensure you are eating a properly balanced diet, avoid any long-term diet that has the word "high" or "low" in it, except perhaps for temporary use. In other words, do not use high-protein, high-carb, low-carb, low-fat diets, as well as low-calorie or high-calorie diets on a long-term basis, otherwise you risk serious nutritional imbalances.

Low-fat and very-low-fat diet use is becoming more popular in treating chronic diseases and obesity. Once fat is removed, most of the remaining energy supplied by these diets comes from carbohydrates, which supply up to 80% or more of calories, in contrast with the average diet that supplies energy from 40% or more calories from carbohydrates and 42% calories from fat. Research of Weston Price, although biased toward animal-based foods, demonstrated that populations that include a balanced distribution of calories from unprocessed dietary fat and unrefined carbohydrates have fewer dental caries. Because there is no phosphorus in fat, increased dietary fat intake tends to lower phosphorus as well as glucose intake levels and protects against disturbances in bone and calcium metabolism. This explains why people on a high fruit diet often do better reverting to starchy vegetables with fat like butter, cream, and oil. Replacing a portion of calories in a high-calorie fruit diet with calories from low-phosphorus high-fat natural raw foods like avocados, macadamia nuts, and coconuts helps maintain safe phosphorus and glucose levels for bone health. 

In an article by Parks and  Hellerstein titled Carbohydrate-induced hypertriacylglycerolemia: historical perspective and review of biological mechanisms, published 2000 in The American Journal of Clinical Nutrition, 71, 412-433, the researchers write: "Current trends in health promotion emphasize the importance of reducing dietary fat intake. However, as dietary fat is reduced, the dietary carbohydrate content typically rises and the desired reduction in plasma cholesterol concentrations is frequently accompanied by an elevation of plasma triacylglycerol." The researchers also note, "Decreasing fat without increasing carbohydrate (i.e., replacing dietary fat with protein) does not appear to elevate triacylglycerol. This suggests that it is the addition of carbohydrate, not the removal of fat, that is associated with HPTG [hypertriaclglycerolemia] in persons consuming LF-HC diets [Low-Fat High-Carbohydrate diets]." Low-fat diets are also associated with depression and suicide, lowered HDL levels (the good cholesterol), and inadequate absorption of vitamins A, D, E, and K.

In Doug Graham's book that recommends a high-calorie fruit diet, calculating nutrients in Autumn Menu Plan: Day One (p. 190) shows a phosphorus level over 1,000 mg and an inadequate calcium: phosphorus ratio of 0.69:1. This plan could be improved by reducing calories from fruit and adding calories from low-phosphorus high-fat plant-based foods. Weston Price hypothesized that there was a mysterious X factor in butter and other high-fat animal-based foods in the diet of healthy people. Although this has been identified as vitamin K (found abundantly in green vegetables), it also seems likely that health improvements resulted from a better balance of nutrients, including balanced levels of phosphorus, glucose, and calcium. For more information on the nutritional value of high-fat coconuts, see: Bananas, Coconuts, and Green Smoothies: Nature's Perfect Foods. Is fear of dietary saturated fat causing you to eat an unhealthy, unbalanced diet? See Is the Lipid Theory Dead? 

If a high amount of calories from carbohydrates in a low-fat or very-low fat diet is good enough to help people recover health, why not always eat this way? Ah...there's that mental association forming again! But these therapeutic diets are used temporarily and are hypocaloric, that is, the total amount of calories they supply is less than the amount needed to maintain bodyweight. The actual amount of grams of carbohydrates in these diets remains similar to the amount in maintenance diets. A 2000-calorie maintenance diet with 47% calories from carbohydrates provides no more than 235 grams of carbohydrates.

On the other hand, a maintenance diet that reduces calories from fat to 10% and makes up the energy difference by increasing carbohydrates to 80% of calories would flood your body with almost twice the recommended amount of carbohydrates, exceeding 400-500 grams or more. Even if all the carbohydrates in this diet are provided by natural, unrefined fruit, vegetables, and other natural foods with a low Glycemic Index, your body's attempt to regulate and remove excess glucose and phosphorus would eventually lead to health problems, like Dr. Bass' lost teeth. 

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