I remember people telling me that when you feel hunger pains that your body is cannibalizing muscle. Is this just faulty conventional wisdom? Im trying to lean out a bit but I shed muscle very easy and I worried about loosing any gains that I have. If I eat I high fat, high protein diet I dont seem to get hunger pains but then even in ketosis I dont seem to be loosing a lot of body fat. Robb Wolf this week on his podcast mentioned that perhaps if someone wasnt loosing weight they do indeed need to cut back on calories. This for me brings hunger pains fast.
Edit/Update I am loosing a lot of body fat now. The only thing that I'm doing different is casual 30 minute walks around the neighborhood whenever I'm bored (so about 5-6 a week). This plus being in ketosis seems to be shedding the fat (lost 5 lbs last 2 weeks). I don't know if I've lost muscle too but I'm not any weaker at the gym so if I have it's been a minor amount. Also, I've been drinking a lot more water which seems to blunt the hunger so although I'm free eating I assume I'm taking in less calories. The only other possiblility is that I started taking Natural Calm before bed. I normally do not sleep deeply but I've sleeping like a rock on this stuff. Maybe the deep sleep is giving me a hormone boost thus easier weight loss ?
When you eat carbohydrates, the body releases insulin to drive the blood glucose level down. However, even when the glucose level has gone back to normal, it still takes a while longer for the insulin level to fall back to normal. During this time, the elevated insulin level prevents fat from being released from fat cells for use as energy, and the elevated insulin level also further suppresses the blood glucose level (hypoglycemia), making it insufficient to supply your energy needs. This is the period of time in which muscle is broken down and its protein converted to glucose for energy.
The hunger pangs come from the insulin-driven hypoglycemia.
So, yes, there is a degree of correlation between hunger pangs and muscle loss.
Some high protein foods also raise your insulin levels, so you might get a degree of hunger pangs from a truly high protein diet though it would be much less pronounced than if you ate carbohydrates. My recommendation would be to cut calories by primarily cutting the protein, but try to maintain a high fat intake, as the latter has negligible effect on your insulin status and should help alleviate the hunger pang phenomenon.
There are basically two types of hunger we need to deal with--post-prandial (after-meal) hunger caused by insulin spikes (discussed by Gary Wu on this thread), and fasting hunger. Muscle catabolism can be caused by either type of hunger, but not necessarily to a significant degree. Also, your feeding strategy can have anabolic effects which can outweigh any temporary small muscle loss.
Insulin is an anabolic hormone, so the net effect is usually to cause muscle gain, not muscle loss. This is illustrated in the GOMAD strategy for muscle gain, discussed in a previous thread ( http://paleohacks.com/questions/5055/putting-on-mass ). So I'm not buying into the notion that insulin spikes cause significant muscle loss.
Furthermore, when you eat a meal, it takes about 3 hours for the hypoglycemia/hunger to hit, but you're still digesting the protein from the meal for 6 to 7 hours. So for 6 or 7 hours after you eat a combined (protein+carb+fat) meal, your gluconeogenesis needs are taken care of by digested amino acids, not muscle protein catabolism.
Regarding fasting, IF practitioners like Martin Berkhan recommend fasting to build muscle, not to catabolize it ( http://avidityfitness.net/2008/01/12/interview-martin-berkhan/ ). Fasting increases insulin sensitivity and promotes growth hormone release, which more than offset the possible catabolic effects. That being said, Mr. Berkhan recommends taking essential and branched-chain amino acids prior to a "fasted" workout to prevent any muscle loss.
In summary, I would not try to avoid hunger if your overall diet and training strategy causes a net muscle gain.