Losing Fat Without Severely Decreasing Metabolism

Hi everyone!
I am pretty new to this site, but already have some questions.
I don’t compete in figure competitions, but like to keep a bikini competitor physique year round.
I have been lifting for about 5 years now, and love it! About a year ago, I read several interesting articles/ hearing about gaining muscle and increasing calories to increase the overall metabolism. (A lot of this was from MindPump if any of you have heard of them). I decided to give it a try myself. I added in about 600 calories a day to my diet and started to really focus on strength training in the gym (5-6 days of lifting a week). It worked and I actually gained almost no extra weight (Besides muscle). I was also reduced my cardio to walking only for about 8,000 steps a day.

That was all over the summer, and now that I am back in school (I am an engineering major) I find that I don’t have time to workout as much. As a result I have gained about 15lbs, which I would like to lose again. I want to reduce my calories and add in HIIT again since I only have time to lift about 3 times a week. I’m worried about slowing my metabolism down and adjusting to the HIIT so that I will always have to keep doing it.

Does anyone have suggestions about how to add in some extra cardio to stay in shape but avoid my body getting used to it? Do you think simply changing the type of HIIT each week would do the trick? Like sprints one week and body-weight circuits the next? Iv’e heard that if you do too much cardio your body will prioritize that over gaining muscle (Not sure how true that is, or at what point that would begin.)
If I’m currently at 1,800 cal. a day do you think decreasing to 1,600 would be okay for my goal, or is that too little calories? For reference I can fit in about 3 hours of heavy lifting a week, and 1.5 hrs of cardio (HIIT or any other type.) I am 5’7" and about 145lbs although a decent amount is muscle.

Thank you for your opinions on this!

I think around these parts we refer to that as G-Flux (G-Flux Redux: Explained - Diet and Nutrition - COMMUNITY - T NATION).

If you want to lose weight, you are going to have to go into a deficit. Eventually, your body will downregulate your metabolism, and you’ll either have to go deeper into the deficit to continue losing weight or you’ll have to reverse diet back up in your caloric intake (and your metabolism will upregulate).

Given what I wrote above, I hope you take away from that that no, you won’t have to always be doing HIIT. You don’t even have to start doing HIIT at all necessarily.

No, changing things up this way will only lead to a negligibly higher deficit, if at all. Also, distinguish between cardio and HIIT. The thing with HIIT is you don’t really adapt, yes, you might become stronger and/or faster but it’s still metabolically costly.

While you can gain muscle while dieting, it’s not too common. Focus on losing the weight (or ideally, looking better) for a while, and then focus on muscle gain if that is your goal. Doing both things at once is really hard, especially as a student.

Do you mean, is that too little calories to sustain you or too small a deficit for it to matter? If it’s the former, no 1600 calories are more than what I take in at the moment (I’m 5 weeks deep into a diet, I’m 6’2", a man, and 163 pounds). If it’s the latter, not necessarily. You could try by just removing 200 calories and wait before you add in HIIT but I’d start with a more aggressive cut, 400-600 calories (probably 400 in your case). Or, wait, are you losing weight already on 1800 calories? If yes, stay there and change nothing. Only once your weight loss stalls should you further your deficit or increase your activity level.

Or you could lift weights 4.5 hrs a week?

check this:

Dr Eric Trexler has some very detailed and thorough articles on metabolic effects of dieting. The short answer is no you can’t avoid it when you’re getting stage lean. How bad the slowdown is will be hugely individualistic, but will invariably depend on how quickly you diet and how lean you actually get.