Writing about meat, Tilden says, 
Those who labor should not eat meat oftener than once a day, and bread, potatoes, or other decidedly starchy foods once or twice a day.
Those of sedentary habits should not eat meat oftener than once every other day, or moderate every day when the temperature is ten above zero or lower. 
When it is possible, meat should always be accompanied with a large plate of raw vegetable salad or a dish of slaw, and cooked non-starchy vegetables.
from Food: Its Influence as a Factor in Disease and Health
Bragg listened to his body and, as he writes on page 78 of his book, The Miracle of Fasting, has a lot to teach us: 
Over the years of following a program of fasting, and with a diet containing an abundance of raw fruit and raw vegetables, my body has become so keen that it practically tells me what to eat at every meal. Over the years on this diet, my body has lost the desire for meat and fish, and my diet is composed of raw fruits and vegetables, cooked fruit, and cooked vegetables with nuts, nut-butters, seeds, raw wheat germ, Brewer's yeast, and legumes. 
This is what my body seems to thrive on, but as I said, I don't like the word 'Never,' because there are times when my body tells me to eat a piece of meat or a piece of fish, or to have some natural cheese or a few fertile eggs. In other words, my body has developed an instinct for the selection of foods
Calories ARE Relevant:
A Critique of Herbert Shelton on Calories	

Some raw-fooders will tell you that they don't believe in calories or the "calorie theory." If an emaciated raw-fooder is making this claim, however, perhaps they ought to start paying more attention to these calories they don't believe in--after all, those who consume adequate calories, in general, are usually not emaciated! :-) 
Definition of calorie. Calories are a measure of heat energy: the amount of heat required to raise 1 gram (1 ml) of water 1°C in temperature. Food calories are actually kilocalories, i.e., 1,000 calories per the preceding definition. The discussion in this paper deals solely with food calories. As heat potential and energy potential are biochemically related, food calories are a measure of the latent or potential energy in the food, and hence provide an estimate of (or proxy for) the energy that you can derive by eating and digesting the food. 
NOTE: Those who recognize the calorie as a measure of the energy available in a particular food may want to skip to the next section if they do not need further convincing of this elementary fact of nutritional biochemistry. 
The basis for common raw-fooder criticisms of calories dates back at least to Herbert Shelton (the principal founder, in modern times, of the natural hygiene movement), and perhaps even earlier (to Arnold Ehret, who promoted what would be known today as a fruitarian-type diet). To illustrate the logical weakness of these objections, let me summarize Shelton's points and comment on them. (The Shelton material below is summarized from chapter 5, "Calories," in The Science and Fine Art of Food and Nutrition (The Hygienic System: Volume II), 1984, sixth edition--first edition was 1935; Natural Hygiene Press, pp. 90-97.) 

Shelton (summary): Calorie requirements are based on an inappropriate standard. Calorie requirements were derived by Voit of Germany, based on what people actually eat. This is inappropriate because: 
•	It's better to base it on what (Shelton thinks) people should eat. 
•	The requirements tell people to overeat, because the average person actually overeats (and the requirements are based on average, or non-rawist, people). 
Reply/Comment: Calories are based on reality. From the point of view of establishing useful estimates of energy requirements, you must consider what people actually eat. Regardless of whether average people may overeat or not, a caloric standard based on sedentary, emaciated raw vegans will not be appropriate (and probably not adequate) for a heavy meat-eater who earns a living via hard physical labor. The standard must serve the people, and not the other way around, as Shelton appears to imply or suggest. As for Shelton's second point above, those who indulge in overeating are usually ignoring a standard based on conventional diets. People who ignore a standard derived from a conventional diet will also ignore a standard based on raw veganism (an extreme diet, in the view of many who follow conventional diets). 
Modern methods for measuring calories are technically advanced. Note also that the methods for measuring energy needs (calories) have advanced considerably since the time of Voit (and Shelton). For more information, see: Recommended Dietary Allowances, 10th edition (chapter 3, "Energy," pp. 24-38), National Research Council, 1989, National Academy Press, Washington, D.C.; and "Energy Needs: Assessment and Requirements," by Yves Schutz and Eric Jequier, chapter 5 (pp. 101-111) of Modern Nutrition in Health and Disease, vol. I, 8th edition, edited by Maurice E. Shils et al., 1994, Lea & Feibiger, Philadelphia. 

Shelton (summary): Calories are merely a system of "fire-box dietetics"! Valuing foods by calories alone leads to a system of "fire-box dietetics" in which refined high-calorie foods are regarded as more valuable than lower-calorie, whole natural plant foods like vegetables and fruits. Humans cannot live exclusively on a diet of refined foods; fruits and vegetables are needed in the diet as well. 
Reply/Comment: Calories are not the whole story. Shelton is partially correct here. Humans cannot live well exclusively on refined foods, and we do need vitamins and minerals, for which vegetables and fruits are an excellent source. Back in Shelton's time, it appears that some conventional medical writers overemphasized the value of calories. However, that is not true today; calories are recognized as only one of the many factors that determine the value of a food--other factors include vitamins, minerals, amino acids, fatty acids, and so on. Inasmuch as Shelton's criticism here is a reaction to now-outdated views extant during his time, we observe that Shelton's criticism is no longer important. 

Shelton (extract/summary): Calories are the least important nutritional factor. From p. 91: "The human body is more than a mere furnace or fire box into which we must continue to shovel fuel. The fuel value of food [calories] is the least valuable thing about it." Shelton goes on to say that calories measure only the combustible part of foods. The portion ignored--ash--is vitally important as it contains the mineral content. Calories also ignore acid and alkali, and most high-calorie foods are acid-forming. Animal tests show that low-calorie foods (whole, unrefined plant foods) sustain life, while exclusive feeding of high-calorie refined foods kills the animals. Low-calorie foods are high in vitamins and minerals. 
Reply/Comment: Calories are one of multiple, important factors. Calories are certainly not the only measure of a food's value; instead they are only one of many factors to measure and consider. Here Shelton is grossly overemphasizing that calories are only a partial measure, and this may lead the reader to the false conclusion that calories are worthless and can be ignored. This part of Shelton's writings borders on demagoguery, in my opinion. 
There is an additional irony here. Shelton argues against calories on the grounds that the calorie model is a narrow measure, as it does not include other factors (vitamins, minerals). The irony is that Shelton's argument itself is narrow--one cannot disregard calories and focus exclusively on other factors like vitamins and minerals. To make this point clear, if we simply note that one cannot live on vitamins and minerals alone, then if we were to apply the same type of reasoning here, we see how the bogus "logic" of Shelton would suggest that vitamins and minerals are also worthless. 

Shelton (extract): Calories depend on digestive strength. From p. 94: "We may add that the value of any food to the individual is partly determined by its digestibility and by the individual's present nutritive needs and powers of digestion and assimilation." 
Reply/Comment: The absorption of any/all nutrients depends on digestive strength. In context, the preceding remark by Shelton was made concerning the limitations of the calorie measure. However, the remark as stated has more general application as well: the same kind of limitations apply to vitamins, minerals, amino acids, fatty acids, and so on. As such, it is not a criticism of calories (alone), but a statement of a constraint that applies to all the "values" our bodies try to extract from the foods we eat. Again, narrowly applying such an analysis only to calories while ignoring its application to nutrients across the board borders on demagoguery. 

Shelton (extract): From p. 95: "A table giving the caloric values of different foods tells us merely how much heat can be produced in the laboratory by burning these foods. Such tables are fairly accurate indexes to the fuel values of the foods listed..." 
Reply/Comment: The above, as with much of Shelton's presentation on calories here, is potentially ambiguous. By fuel value, does he mean the energy value available to the body from eating the food, or is he discussing testing food for fuel value only as one would assess the value of gas, coal, oil, or wood in a furnace? The latter seems unlikely, so is Shelton contradicting himself here in now agreeing that calories do in fact give close estimates of their available food energy? 

Shelton (extract): Calorie requirements are highly variable, hence dubious. From p. 95: "The amount of heat and energy required by various individuals varies so greatly with the conditions of sex, climate, occupation, age, size, temperament, etc., that food values based on the calorie standard are of no practical value." 
Reply/Comment: Shelton's claim is illogical and overemphasizes individual differences. Let me restate the above, with a few minor changes, to illustrate the defective logic: "The amount of vitamins required by various individuals varies so greatly with the conditions of sex, climate, occupation, age, size, temperament, etc., that food values based on the RDAs (recommended daily allowances) of vitamins are of no practical value." Once again, Shelton is overemphasizing differences due to individual variability, and his demagoguery here may lead readers to the false conclusion that calories should be ignored. Shelton appears to be trapped in the binary thinking mode that is a very serious limitation of the natural hygiene approach. 

Shelton (extract): Eating for calories can only lead to trouble. From p. 96: "It should be easily seen that a system of feeding based on the caloric or fuel value of foods must inevitably lead to mischief." 
Reply/Comment: Today, no one advises eating solely for calories: other nutrients are also important. If one eats only for calories, Shelton's remark is relevant. However, no rational person would try to live on a diet of, say, only cheesecake and cookies (no matter how good they taste). At the present time, no reputable nutrition expert would suggest eating ONLY for calories; instead, reputable nutrition experts recommend eating a variety of foods to get adequate vitamins, minerals, fatty acids, protein, AND calories. You need all of those factors--you need vitamins, minerals, fatty acids, protein, AND you need the energy from food that the calories are a measure of. Once again, Shelton's comments here are outdated. 
Calories are a useful measure of energy. Over and above the calorie standards suggested for individuals, the calorie is a useful measure. It provides the best estimate of the energy one can get from a particular food. Calories are also used to measure not only the energy quotient of a food, but individual basal metabolic rates, as well as the bodily energy required for various daily physical tasks. They are not just a measure of food energy, but biochemical energy--which also applies to the energy required for bodily tasks and functions that no one can escape. You need energy from food to survive and thrive. Contrary to some rawist fantasies, food is not just a source of building materials--it is also an energy source. We know that without energy, a pile of building materials cannot be transformed into a building. Similarly, the human body cannot build--or live--without energy. 
In summary, the calorie is not only a convenient, but a useful--and tested--model of the reality of our energy needs. 

Breatharianism: energy from the ether, or just hot air?

No confirmed breatharians (or yetis either). In closing this section, it is worth mentioning that before Shelton's time, the fruitarian extremist Arnold Ehret (note: I am a former follower of Ehret) also popularized the idea that you did not need to eat food to get energy. In more modern times, the term "breatharian" has been coined to describe a person who supposedly gets energy strictly from the sun or from "prana" in the air and does not need to eat. The problem, however, is that there are no scientifically confirmed cases of breatharianism (no surprise there; as yet, there have been no confirmed sightings of any yetis either). 
Have your cake and eat it anyway. Even worse, a recent advocate of breatharianism was found to be a fraud (he said he did sometimes eat hamburgers but since those are not real food, his view was this showed he was actually living on air ;-) ); and a currently active advocate of the practice advises her followers that they can be breatharians and eat whenever they want to, for fun or for social reasons. Quite frankly, that is suspicious and ludicrous--it's like saying you can be a raw vegan but eat meat anytime you want to (and implicitly, in any quantities), for fun or for social reasons.