my appointment with a "trainer" FEEDBACK PLZ!

How does cardio burn muscle when my heart rate goes over 165 bpm??? I strength train, and alternate with cardio-- so I am unsure how this can occur.

How will my body composition stay the same when I incorporate carbohydrates back into my diet? I am having a hard time wrapping my head around this one.

Couple of things. When you are at a low body fat percentage, it is SO hard to reach that goal BF%. Your body's main fuel is Glucose - Carbs. When it has no carbs it MAKES them in a process called glucogenesis. Your body will chain together amino acids (from protein, either dietary or stored) with fatty acids and lipids from fat, (also either dietary or stored).

If you have no carbs in you when you hit the afterburners during your workout, your body will start making its own fuel, the key to low carbing is to get your body to EAT it's own fat stores when you undergo glucogenesis. If you do high heart rate HIIT you will see more catabolic effects, and no amount of eaten protein can make up for the extreme energy needs that you have on the cellular level (won't bore you with the details, but ATP-ADP transfers), and you will see a reduction in stored muscle.

So he is on some levels correct. If you want to get a shredded look, I would really recommend supplements. Find yourself some good BCAA's to take right before your workout, those will help give your body the proteins it needs to stay away from raiding muscle tissue - Creatine Monohydrate is one of the only proven supplements out there, And while the NCAA no longer provides that supplement for their athletes, they don't forbid it. It is one of the most studied and proven muscle building supplements out there.

The last one is a good multivitamin. If you cut calories hard (-20% TDEE), you need to be sure that your diet is whole. Better safe than sorry in my book.

Cardio only on your weightlifting days off (and stick to the steady state stuff), and when you lift, you need to lift HARD to shock your muscles into growth, give your body 2 or even 3 days off from hitting the same muscle group, and then lift HARD again. You should be getting close to failure near your tenth rep or so.

Notice I didn't say "to failure". It's always best to leave a little in the tank, but you should honest to god walk away from a lift going whew, that was challenging.

HIIT is a tool to be used by athletes looking to improve their conditioning and performance, like a wide receiver in football running down the field every play. It's not such a good tool for a heavy linebacker looking to have a lot of weight to hold the line. HIIT does nothing for body composition. Only in those who are overweight is it an effective tool at triggering more fat loss at a plateau, or whatever the rationale may be.

I hate to say this, but he is correct. This is part of the basis of the TNT Diet for example. It works very well for shaving body fat. Worked wonders for me...however, it's a short-term thing, as the trainer noted. Also, cardio does burn muscle. This is one of the first posts I think a trainer was actually correct for a change. I would say go back to him ASAP. If you don't believe this, I recommend doing some research. The only thing I would add to what he said is you also need to get a good amount of fiber as well. What sucks about this plan for most people is that this means you basically remove all fruits and virtually all carbs, which is really tough to do for most people. Good luck!