Gaining muscles makes it hard to gain weight?

Well, after reading hundreds of threads here, and listening to my personal trainer, here's what I THINK I've picked up on the subject. First, a bit about what I want to do with my body because it sort of sounds like your situation.

I lost about 75 pounds a few years ago, got down to a weight I was happy with (5' 10" at 145). I'm now 52 and am probably more active and healthy than I ever have been; picked up mountain biking, walk alot, etc etc.

But...I have some flabby areas here and there, and I wanted to BUILD MUSCLE (note "build") so I could be both a stronger mountain biker AND to be in a condition where I just look a bit better, more toned...plus weightlifting is good for building bone density, etc etc.

So this winter I joined the local gym and hired a personal trainer to get me going on a free-weight lifting program. Explained what I wanted, foolishly expecting that if I continued to eat at maintenance, my muscles would take the small to moderate amount of leftover flab here and there to grow, and I would magically grow muscles and lose flab SIMULTANEOUSLY. Magic.

Uh, no. Here was his first explanation of what I needed to do, and should expect:

If I wanted to build, and have stronger, muscles, I should plan on eating more than maintenance calories. I should expect to gain weight over the winter if I want to build muscle. Some of this weight will be fat; some will be muscle. Expect it, and don't freak out (as I'm sitting there freaking out).

We will work on building muscle by lifting progressively heavier loads. I will also put on more fat. That's the primary way to build muscle--your muscles need excess calories to put into growth. Muscles will not necessarily turn to your existing fat stores to grow (flabby upper arms, a bit on the belly, fat stores on my thighs) since I am at a normal weight.

But to provide that energy for muscles, one must provide excess calories. Muscle will also not appear overnight; it takes time. Fat will also increase--not like I'm going to all of a sudden become obese, but I will put on a few pounds of it.

However, when spring comes, and I pull out the bike and get more active, cardio-wise, I will be stronger, with more muscle mass. Adding cardio, and now working carefully both on cutting calories and ensuring I maintain (not grow, necessarily) my muscle mass (keep lifting to maintain), I will lose much of that fat.

What will result after this winter of heavy lifting (very little cardio other than morning walks/hikes of 3-5 miles/day) and eating over maintenance, and then a summer of biking and maintaining muscle mass, I will likely have met my goal of building muscle, decreasing body fat, becoming stronger, and be in a better place, health-wise.

Sorry this is so long, but I mostly wanted to give you this perspective to think about, and let you know that this sort of thing--changing your body condition--takes TIME and PATIENCE, and you might have to re-think what you think you know. It took me by surprise that I couldn't just simply lift heavy weights, eat at maintenance, and grow muscles AND lose fat all at the same time. It's a journey, and one, after working it out in my mind, I'm willing to take.

It blows me away that I'm now drinking chocolate milk, whole milk, whole-fat yogurt, etc. and lifting heavier weights than I ever have. I put my trust in my trainer, and so far I'm really fascinated by the whole thing.

As he said to me early on: I know how to lose fat. Don't worry about gaining a few extra pounds of it. The benefits of weight lifting are so, so worth it.

A surplus by definition means weight gain. If you don't gain weight, you are NOT eating at a surplus. If you are lifting and not gaining you are eating at maintenance (this is your real maintenance, not an estimate given by a website) and need to increase what you eat.