If you are losing a few pounds each day
Who is talking about losing a FEW pounds each day? We are talking about losing 1 pound per day.
It implies glycogen and fat stores are getting low.
Fat stores are NOT getting low anytime soon. Glycogen stores will get low if we burn them off too fast. We have to go slow to avoid this.
Muscle glycogen is the first to go--about 4 pounds weight loss.
ONLY if we go too fast. We must be very careful NOT to stress our muscles so as NOT to burn glycogen rapidly.
After Muscle glycogen, liver glycogen is released by order of the brain, to nourish it.
The brain is another story. There is nothing we can do to reduce our brain's requirement for 600 calories or so a day of glucose, which is why we can't live on a mostly fat diet as some foolishly suggest.
Avoid depleting liver and muscle glycogen by resting and snacking often.
This is partly true with respect to liver glycogen. As I noted above, what is used by the brain must be replaced from food intake, otherwise we will burn muscle. With respect to the muscles, the correct way to avoid depletion is to SLOW DOWN and thus burn mostly fat.
As for resting, that is irrelevant. Resting doesn't rebuild glycogen stores--eating food rebuilds glycogen stores. And there is no difference in calorie consumption between walking slowly but steadily without stops and walking slowly but steadily with occasional stops. Then again, if you want to rest, by all means rest. The important thing is to walk slowly so as to avoid burning glycogen.
As for the business of eating often, the scientific basis for this is that we want to avoid blood sugar to spikes, since this will cause insulin to be released and may cause precious carbs to be converted into fat. To avoid this, eat low-glycemic index foods, such as plain rolled oats. Avoid easily digested sugars.
Fat will burn off slower, but steadily. If you are "pushing" too hard with too little food, your muscles (protein) will be shrinking as you burn them up.
Finally, the good doctor says something intelligent. This is just what I have been repeating over and over. You must go SLOW to burn fat. Otherwise, you will burn glucose until you run out of glycogen reserves, at which point you begin converting muscle protein to glucose.
To lose 7 pounds in one week probably represents 3 pounds of water loss, 1 pound of muscle glycogen, and 3 pounds of fat. No, it is not a healthy diet".
Now the doctor has changed his mind. He is talking about losing 1 pound per day, just as we originally agreed. Water loss is irrelevant. The loss of muscle glycogen is serious. This loss implies we were walking too fast. We need to slow down to avoid this. At 1700 calories/day of food intake (a pound of oats mixed with non-fat dried milk to boost protein percentage and reduce fat percentage), of which 1200 is carbs, 300 protein and 200 fat, we must devote 600 carbs to the brain and that leaves only 600 carbs for the muscles, with the muscles burning 3500 calories/day of fat (this implies 15% glucose, 85% fat).
The doctor sounds like he is knee-jerk reacting to the same question he has been asked umpteen times by fat and lazy middle-aged slobs who want to continue to feed their faces constantly but lose weight at the same time. "No, you can't lose weight fast." The doctor simply can't conceive of the concept that someone is actually doing slow but steady exercise for 8 to 10 hours/day like our ancestors used to do. This is something unheard of in the modern world, after all. Either you sit on your ass watching the tube all day, or you rush through some super-stressful routine at the gym. One extreme to the other.
Again, in order to get past the hysteria, I suggest you reflect on how our ancestors lived and how primitive peoples live today. Feast-famine is the norm in nature, so how is it that we humans managed to survive this long if we aren't well adapted to feast-famine?
Alternatively, read this trip report http://www.golite.com/team/athletes/coup/ct_report.pdf by the guy at Golite. At the end of this trip report, he notes that he lost 1.25 pounds/day by walking slowly but steadily. How does the doctor explain that?
If you read this report closely, you'll see that this guy ate approximately 1 pound of food/day (he planned on 2 lbs per day, but a bunch of food spoiled and he had some left over at the end). His food choice was very poor: dried fruit, which has a high glycemic index, and nuts, which are mostly fat. He was probably lacking to 50-100 grams of protein that we need to repair tissues. A much better choice would have been plain rolled oats, with a little non-fat dried milk mixed in to boost protein and reduce fat percentages, and preferably eaten raw, so as to reduce glycemic index and also save the weight of a stove and fuel.