Carb refeeds stimulate weight loss in appropriate candidates. Here's the basic gist of it.
I'm sure you're familiar with insulin. It's the storage hormone. It tells your muscles to store glycogen, it shuttles amino acids into cells and it stores fat in fat cells. The Primal Blueprint stimulates fat loss by regulating your blood glucose, thereby keeping insulin levels stable and low. This prevents fat accumulation and leads to fat loss over time.
There is also insulin's anti-hormone: leptin. Leptin is the hormone that tells fat cells to release fat. It's actually leptin resistance that leads to morbid obesity - the insulin keeps shuttling fat into cells, and due to leptin resistance, your brain never receives the signal to release the fat your cells are storing.
In a normal, healthy person, as insulin rises, so does leptin. This has a counter-balancing effect. As insulin stores fat, leptin releases fat. A person with a proper diet will not gain fat because the hormones will work in harmony. Now, here's the issue:
As your weight normalizes and your hormones stabilize, your constantly balanced insulin levels will lead to very low leptin levels. This tends to happen when people reach "normal" levels of body fat. You know, when people have those last 10-15 pounds that they just can't get rid of. The low levels of leptin create that plateau effect. Your body just can't release that fat, no matter how low you drop your carbs. Well, that's because the lower you drop your carbs, the lower your leptin levels fall and the harder it is to release fat cells. You already have stable insulin, so low-carbing it won't cause anymore fat loss. It's actually counterproductive. That's where the carb refeed comes in.
The science behind the carb refeed is by eating lots of carbs over a small window (I do 48 hours), the insulin spikes boost leptin levels. Between the elevated thermogenic levels in the body from all the carbs (fats are not thermogenic outside of MCT's like coconut, carbs are much more thermogenic) and the sudden huge boost in leptin from the insulin spikes, your metabolism goes into overdrive. When you come off that 48 hour carb refeed, your metabolism is now a hot burning oven, so when you snap back into low carb, the residual metabolism boost allows you to release extra fat that you wouldn't normally be able to release due to your low leptin levels. Now, there's a kicker: you have to figure out how to not store excess body fat while carb refeeding. This requires keeping fats very low - under 40g. You can't cook with oil, you can't eat red meat, etc. It's super lean chicken breast or very lean fish for you. When I do a 48 hour carb refeed, I shoot for 250g of carbs each day for a total of 500g of carbs over the 48 hours.
Now, it's important to use complex carbs in this equation. Vegetables will not work because they don't spike your insulin, and the big insulin spike is crucial. Fruit is a poor choice because of the fructose. Your carbs must be starch, and they should come from skinless yams as a first choice, and white rice or skinless white potato as a second choice. Properly soaked beans can also work (black, pinto, kidney, etc). If you are a man, I recommend eating one small piece of fruit with 2 of your meals - preferably the pre- and post-workout meals. If you are a woman, I suggest half a serving of fruit with the same 2 meals.
The amount of carbs you intake will vary wildly, and you need to tune it for yourself. As a 5'7", 139lb, highly active 24yo male that works out 6 days a week, 250g of carbs is great for me. Body builders that are over 6 feet tall and weigh in over 220 pounds will frequently eat 500-600g of carbs. Conversely, sedentary women would want to shoot much lower - maybe more like 100-125g. It may not be a whole lot more than they normally take in, but 100g of carbs from fruits and vegetables have a totally different effect than 100g of carbs from yams! The source is most crucial. Btw, the 250g figure includes all carbs. My carb cycle typically includes 1.5 pounds of a lean protein, 6 yams and 2 pink lady apples each day, plus whatever other green vegetables I take in. My total is always around 250g.
If you still have 48lbs to lose, I would not suggest carb cycling. If you're still too sensitive to carbs, it could backfire. You need to wait until you get down to a more average weight and your hormones stabilize. Being 48 pounds overweight, your leptin levels are probably still elevated. Have you hit a plateau? I would NOT suggest carb cycling until you hit a weight loss plateau. I started Primal in pretty good shape, and over the first 6-8 weeks, while it made me feel a whole lot better, I hardly lost any fat. My weight stayed the same. Since I've started carb cycling, I've lost 6 pounds of fat while increasing my strength and I've been on fire lately.