Don't let any book be the last word. Include your doctor in the decision-making process. Let's be clear about one thing, though, before we go any further. Deprivation dieting is probably more foolhardy on the trail than at home because you are demanding a lot more of your body. There is no way you will have an enjoyable outdoor experience if you are hungry, worn out or just plain sore.
Women require somewhat less, but still much more than they regularly take in.
You also want to remain consistent with the dietary philosophy you have established within your daily life. But, reality checks in if you go overboard to eliminate the spare tire. A 35-pound pack will weigh a lot more on Sunday if you've starved yourself on Saturday. That's because activities like hiking, cycling, canoeing and kayaking go beyond fun and actually become work work for the body on a level that exceeds appropriate energy depletion to promote weight loss. Work that makes you ache.