A theory I've been experimenting with lately is the use of short bulking and cutting cycles. An example of this would be intermittent "dieting" (calorie restriction) to improve fat loss results. Anyone who's gone on a calorie restricted diet eventually stalls, and some of the common reasons for this are:
1. You weigh less than at the start and your lower daily calorie expenditure at this weight has not been adjusted for
2. Hormonal changes such as a drop in leptin, thyroid and nervous system output
3. Generally when dieting motivation to move and fidget is lower, and reduces NEAT (Non-exercise activity thermogenesis)
Once stalled, typically the next step is to reduce calories you are consuming and/or increase energy output through additional exercise (often the dreaded cardio).
However one thing that we do know is that by taking a "diet break" and increasing calories for a period of time, some of the keys hormones especially leptin which has a large role to play in our metabolism, begin to return to normal levels. Generally the longer you have been dieting the longer it'll take for your hormones to return to normal (if they do at all).
A new study looked at the impact of putting 51 obese men on 1 of 2 energy balanced diets for 15 weeks
Group 1: Continuous calorie deficit.
Group 2: Intermittent (yet larger) deficit. 8x2 weeks blocks in a deficit alternated with 7x2 weeks in maintenance.
Even though both groups were matched in terms of total calories, the Intermittent dieting group showed significantly greater fat loss. Fat free mass loss was similar.
Continous lost an average of 8 kg fat
Intermittent lost an average of 12.3 kg fat
It's obviously hard to pinpoint exactly why intermittent dieting was so much more successful, but I would imagine the main 2 reasons would be:
1. Psychological - dieting non stop for long periods can really take it's toll both physically and mentally, and having a break to eat at maintenance calories would likely improve mood, lower stress and improve adherence.
2. Hormonal - as mentioned, dieting harder for 2 weeks than giving yourself a break of 2 weeks would be sufficient to reverse some of the negative impacts on hormones, especially leptin.
If you plan on going on a cutting phase anytime soon, try this theory for yourself and see how you get on. The same could also be applied to a bulking cycle.