TL;DR – It’s either your volume, consistency, diet, or genetics.
You’ve been going to the gym for a while now, but you don’t feel like you’re getting stronger, and you know you’re not getting any bigger. The good news is, it’s possible to isolate the variable(s) that are causing this. The bad news, you have to actually be honest with yourself.
- Consistency: Stop being lazy, undisciplined, and presumptuous.
This is, by and large, good advice in general. It turns out this applies in the gym as well. If your body isn’t forced to adapt consistently, it’s not going to make any long term adaptations, aka muscle growth. It will rise to an occasion, but if there’s no reason to stay in that particular shape, it will dissipate. If you want results, work out consistently. If you can’t get a full workout, hop in for 15-20 minutes, do a few heavy sets, and at least maintain your muscle.
- Volume: Progressive Overload (Check Wiki for studies)
One factor of your lifting woes could be due to not forcing your body to undergo more stress. The body needs to be challenged in order to grow. It’s a pretty straightforward concept: the more you’re challenged, the more you’re going to adapt. The body is all about being as efficient as possible, and your body will adapt to a constant training volume. Because of this, you need to change things week to week: add more sets and reps. Do this over a couple weeks, deload, and repeat with slightly higher weight. Boom.
- Diet: You aren’t eating what you think you are.
This is honestly tied with consistency for being the most simple step: if it’s not the above, then your diet is off. The fast/slow metabolism excuse is bullshit (save for actual, diagnosed conditions). If you’re really active i.e. working a manual labor job, constantly playing sports, walking or biking instead of driving, you’re going to have to eat an immense amount of food. Start making shakes or downing lots of peanut butter (or make shakes with peanut butter) to get your calorie count up. Make sure your protein is within an acceptable range (0.7-1.0g per lb of body weight). Try tracking what you eat in a day using MyFitnessPal or something. Make it work, put some effort in. You aren’t a special snowflake (unless you’ve been diagnosed as one).
- Genetics: You might be at your limit.
You probably won’t have to worry about this for the first decade of working out, at least from what I’ve gathered on the subject. Without steroids, there’s a genetic cap to what you’re going to be capable of. You can either focus on some new fitness venture, or take steroids and go beyond your natural capacity. I think steroids are dumb, but it’s your body.
Try troubleshooting these four areas, probably in this order. Gaining muscle is a science which means that, lucky for us, having incorrect calculations is easily fixed. Good luck, and may the gains be with you.
I don’t think this Master Shake picture is ever not relevant.