Oooh, ooh, pick me, pick me!!!!
Seriously though, this is a really interesting concept. It's closely tied into IF theory and ketogenic components. I'll assume you already have a basic understanding of glycogen depletion, etc.
I will readily admit a bias as well; I LOVE reading the body-building stuff, their nutritional approaches fascinate me. I can recommend T-Nation for some of their articles; if you just search 'carb cycling' in the articles section, there are several short publications about the theory.
One in particular (titled 'Research Approved Carb Cycling') compares several approaches, and concludes with a recommendation similar to 5:2. It references a study out of Manchester by Michelle Harvie (Ph.D) that was originally presented in 2011 (San Antonio Breast Cancer Symposium). Comparing a traditional Calorie Restriction diet, a Ketogenic diet, and an Intermittent Low-Carb diet, the results were fascinating. The carb cycling group lost more weight than the calorie restriction...AND equal to the ketogenic group. Which means - to paraphrase - in this case, people who only ate low-carb 2 days a week experienced the same weight loss as those who ate low-carb 7 days a week! The caveat being that the keto group resulted in slightly higher levels of improved insulin sensitivity (I think it was 14% vs 22%?). This is pretty exciting because eating low-carb 2 days a week is much easier to do rather than every day, and therefore average compliance is likely to be much higher.
The recommended method is to eat normal carb on your workout days, and then two days a week (either separately or consecutively) when you're NOT working out, you eat lower calories AND lower carbs for 'restriction' days. Low-carb days should keep total carb to <50g, and calories are usually ~%60 of your normal daily amount.
As a brief and rough example:
Sun: Active Recovery, Low Carb
Mon: Full-Body Workout, Normal Carb
Tues: AR, Low
Wed: Full-Body Workout, Normal
Thurs: AR, Normal
Fri: Full-Body Workout, Normal
Sat: AR, Normal
There are more complicated methods that include a 'high' carb day in addition to the 'normal' and 'low' periodization; at that point, I think it's getting kind of ridiculous. And it should be mentioned that carb cycling is an advanced method of dieting; ideally you'd have some familiarity already with estimating macronutrient ratios and calories. A less obvious usage of carb cycling can also be found with Martin Berkhan's 'Leangains' approach, which simply includes a shortened eating window every day, and eating higher carbs and calories on workout days and lower carbs/calories the rest of the time. He also has some interesting articles interpreting some nutrition/fitness/diet studies that have come out in the last decade-ish. Mark Sisson (MarksDailyApple) has also spoken about carb cycling/restriction and IF before, with a distinct paleo slant to things.
Personally, I would be fascinated to see a study that compares ketogenic, calorie restriction, carb cycling AND IF(probably the Eat Stop Eat, or 1-day fast methods) diets. I think that there are a lot of interesting correlations between short-term calorie restriction (or fasting) and possible effects on refreshing metabolic functions and overall health markers. Note that I've said 'correlation' to avoid the cause-correlate argument; my personal bias is strongly supportive of the benefits attributed to IF and therapeutic fasting. I think it's also a great deal healthier, and easier, than the gritty side of constant calorie restriction. But I'm sure it'll all get studied at some point.
'Hope this helps!