Gained 1 Kg with lifting weights - confused

I'd suggest 1200 isn't enough so upping it is a good idea, also it's probably a combination of muscle and any increase in calories are likely to show a small gain until your body adjusts.

it will be water. i can go up by a couple of kilos for two days post weight training, especially if i'm using big muscles.

and yes, eat more.

lifting weights on a calorie deficit is not pointless as it will help you to maintain what muscle mass you already have.

Right so male 5'9/5'10. I was 87.3 kgs last week. This week I started weight training plus cardio and I have gained 1 kg and increased my calories, because I was feeling really weak and tired eating 1200 calories a day.

Now I know that once you lift weights you retain water and stuff. So I should be gaining weight. But is 1kg normal in a week?

I can gain 1kg in a day.unless you weigh yourself daily, you'll never know whether it's normal or not.

Ok so you're still trying to lose and just trying to retain muscle. Have you tried calculating your tdee and deducting 15-20% (I'm not sure how many lbs in a kg but the less you have to lose, the smaller your cal deficit should be). This should give you a better estimate of how many cals you need to eat whilst still losing weight. FYI when I work out a lot the scale often doesn't move or goes up but I've learned that it must all be water as when I stop working out I get big drops over a couple of weeks and my size decreases so the working out is making a positive improvement even if my scale doesn't show it.

you can't lose fat and build muscle at the same time (okay there are specific exceptions, e.g. noob gains)

if you're eating at a deficit (less than you burn off) for fat loss, then train and eat to maintain lean body mass, i.e. keep the deficit moderate, and the leaner you are already, the smaller the deficit should be (or the more you should eat), because the leaner you are the more likely you are to lose lean mass along with the fat.

if you are already lean and want to gain muscles, you need to eat at a surplus, i.e. more than you burn off, and train really hard so that the weight you gain is muscle, and not fat. YOu can expect some fat gain when doing this, but by keeping the surplus moderate you minimise it, and also you can do a cut (i.e. eating for fat loss for a while) to get rid of it.

You can't do both at the same time.... occasionally though, in people who are new to weight training who are overfat, gains in lean mass while eating at a sensible deficit do happen, so if you're in that category, eat at a sensible deficit for slow fat loss, and it's possible you may gain a little muscle while losing fat. Then, when you're lean, you can eat at a surplus and start training for muscle gains.

Sounds good. Most people seem to like to get down to a good weight/bf% before thinking about bulking. Otherwise it can just make you feel even more fat . Keep up the strength!

Yes I do think you should keep up the weight training. If you eat at a large deficit (I know you've upped your calories now) then you will lose weight quickly but you will likely lose more muscle than fat.

By keeping the deficit small and working your muscles using weights you will keep a lot more of your muscle and the majority of what you lose will be fat.

Also the weights should help you look more toned as you approach your goal weight. I made the mistake of eating at too large a deficit for a long while and even though I was often using weights to strengthen my muscles, my body didn't have enough fuel to make the training worthwhile. I am left looking untoned, almost anorexic and with more extra skin than I could have hoped for if I'd trained and eaten properly from the start.

I'm at my goal weight but I'm now trying to reverse the damage by bulking up a bit again and eating and training properly to recomp my baggy body (I'm basically trying to get back to where you are now!). I don't think your body will look anything like you desire either without a good amount of calories and strength training.

Eating at a reasonable deficit and strength training to maintain your lean body mass (muscle) is the best route for you to take right now IMO

Weight loss may appear slow or even seem to halt at times but it really is just water and your body trying to repair the muscles. As I said before, I can stay the same or gain while I'm doing a lot of training but as soon as I have a couple of weeks off, any added weight and more just falls off as my body releases the water because my muscles no longer need it for repairs because they aren't being worked hard.

I find it easier to accept that I am really losing weight and that the scale is fooling me if I feel my biceps after training, they get really pumped up but I know muscle doesn't build that fast so then I imagine all the muscles in my body are retaining like that for repairs (with water and whatever) and I find it easy to imagine why my weight is staying the same or rising temporarily.

Stick with it and reevaluate your progress in a few weeks.

In your opinion would weight training still benefit me if I ate at a deficit? The aim being enhanced weight loss and retaining muscle mass.

Absolutely. Not only will it help to protect against losing muscle mass along with the fat, you will also see big strength gains. While gaining actually muscle mass is not possible eating at a deficit, you can still gain a lot of strength with the muscle mass you already have. So definitely hit the weights, keep on making sure you're eating enough and also that you're getting enough protein. Aim for slow and steady fat loss while not feeling deprived. Weight training also helps with bone strength, providing you're eating enough calcium, so there's that too. Bone loss is another risk from very low calorie diets.