I have been going to the gym for a couple of weeks, mainly because I can't run outside now that the temperature and air keeps fluctuating. It's made me sick twice in a month. I like the convenience though of being able to do a little weight lifting in between the treadmill and bike sets I do.
I'm terribly weak in my upper body though, it's sad - but that will change in a few months
That being said, I read ALOT about anything I do before I do it so that it's done efficiently and effectively. So, let me drop some knowledge on you with links from my Evernote stuff.
1. Is there any truth to the myth of heavy training with few reps vs light training but more reps (I found one report online that suggests heavy training is better as it helps increase the metabolic rate thereby helping you burn fat even while asleep)
Any weight-bearing exercise if done for an extended period of time can help your metabolism stay elevated for 24+ hours after you are done. (Discussed in one of the slides here:
20 Fitness Myths Slide Show | LIVESTRONG.COM)
Few reps helps with "bursts" of strength, but not with endurance - just like football players or sprinters in running can go very fast for short bursts, but tire quickly and can't maintain their speed for long if they have to run longer distances. This is because their muscles, tendons, and skeletal system can't maintain the pace because they haven't been properly conditioned.
What's more, muscles, tendons, and the skeletal system (in that order) develop and a different pace than one another. So when you're tearing your muscles by lifting increasing amounts of weight, your tendons and bones aren't building up to support that added gain.
This is one reason you'll see people saying fewer reps of higher weight is better at getting "stronger", because most people's tendons that attach muscle to bone, and the bone itself is only able to support it for that long. What they don't tell you is that you end up becoming an injury waiting to happen.
The above doesn't really get talked about much outside of running-related websites, because such injuries occur due to the higher amount of stress put on the lower body while running. I'll discuss the related points to all of this in your next question.
2. I take whey supplements. Now from what I gathered on Yahoo answers, all they do is ‘fill in’ the muscle tear which happens during workouts, thereby negating the need for a complete 24-36 hr rest period before training the same body part. Now the thing is I work out each particular body part only once a week, so how does whey help?
REST is very important to building muscle. If you workout everyday without giving your body time to repair itself, you'll end up "LOSING" muscle due to your muscles not being able to perform properly and your body spending unnecessary amounts of energy on constant repair.
It's why any training program for runners (again, cross-training gives great insight into body recovery and enhancement) mentions only adding 10% or so progression each week and only workout out 3-4 days a week until you're pretty advanced and doing 20-30 miles a week so that you know what your body can handle.
The real benefits of a workout comes AFTER resting. Allowing your muscles adequate time to recover, such as only working one muscle group a day, another the next day, etc. without crossing over into the same muscles you worked out the previous day will ensure that when you do workout those muscles again they are able to perform better over time.
How to Build Muscle: The Definitive Guide to Building Muscle | StrongLifts.com
I had another link that actually explained the whole resting thing in great detail with interesting training plans but it seems Evernote didn't sync it.
3. I have noticed that I have gained 2.5 kg since I joined, despite the fact that I do 20-30 minutes cardio each day (5 days a week). Now when I come back home I eat a little junk food, like a small pastry, chicken lollipop etc. Do you mean to say that the cardio I do ‘helps’ keep the weight increase to ONLY 2.5 kg (meaning to say that without the cardio, I would have ballooned up by 5-6 kg? I find this highly unlikely because before I joined the gym, I used to eat this same junk food without any exercise and I would gain 2-3 kgs.)
3,500 kCal = 1lb of fat. It's actually about 4,500, but that'd include essential parts you'd use while working that pound off. Interestingly enough, 1lb of muscle burns about 35-50 kCal per day. So, as you gain muscle, you'll increase the rate at which you burn that off as well.
Here's the thing. You should be eating MORE Calories than you actually need the days you are working out to give your body enough to use when exercising. As you workout, you'll learn about how much you need to eat to maintain your weight.
From your question I can't really tell if you are discussing gaining muscle or fat. If it's fat, you need more cardio. The general rule of thumb is that if you're over 150lbs, you lose about 124 kCals per mile if you're at your proper (80% of max) elevated heart rate for over 25 minutes in that session.
So, if you're trying to lose weight in addition to building lean muscle, figure up how many Calories you're eating. Then figure up how many you're losing while lifting weights, Subtract the later, then add in more time on the Elliptical, Bike, or Treadmill (and don't go by their counters. Most bikes and treadmills are off about 10-15% in accuracy for Calories burned, and Ellipticals are off about 45%).
In a typical Gym session (3 times a week) I tend to burn about 400 kCals from my 3 mile run, about 120 from dumbells (I use a mix and match from here:
50 Great Dumbbell Exercises « Soloflex ), and then another 100+ from 30 Mins on a bike.
Using that calculation, I know that I can generally burn off 2.1 lbs of fat a month at my current mileage of running and more while working out at the Gym without gaining weight given my current eating pattern.
And actually, as you get more fit, you tend to cut out a lot of junk food and soft drinks because of the endorphins released as you get healthier. You want to see more and more improvements, which subconsciously turns into better health habits. This decreases your fat as well.