Am I working out too hard to lose weight properly?

Anatreptic

I exercise 6 days per week for one hour with a 5 minute or so warm up, so 65 minutes. My average heart rate is approximately 180. I say approximately because sometimes it's between 178-185. It is never LOWER than that during my workouts, (this isn't including the warmup). This is approximately 90% of my maximum heart rate. By sustaining my heart rate at this level for this amount of time, am I negating fat burning? I need to lose weight, not build muscle.

As for perceived exertion, at 175-185 I don't feel like I'm really DYING exactly. My breathing is deep and even, I'm not dizzy or lightheaded, I can drink water (which means skipping a breath) without falling over. I feel like I'm cheating myself if I'm not doing my absolute hardest during that hour. Am I wrong?

What should my sustainable heart rate goal be?

NikoM5

The "fat burning zone" is garbage. For all intents and purposes, you can't work out too hard to lose weight properly.

iorahkwano

What activity are you doing as your workout? If the intensity is too high & your heart rate is extremely high, your body will burn glucose (stored in the muscles) instead of fat because glucose is the fastest fuel to use since it does not need oxygen to be converted to energy. When your heart rate is lower and you are doing low-to-moderate intensity, your body uses its fat stores since the energy demand is not as sudden & intense.

For sprinting, rowing, push-ups, wrestling & shovelling, (Things that make you breathe hard), your body is using glucose.

For swimming, walking, biking, light jogging (Things where you breathe comfortably), your body is using fat.

Maybe if you feel like you are not losing fat, you should try doing a moderate-level activity instead of a super high-intensity one that's using muscle glycogen as fuel. Instead of running on the treadmill at 8mph for 30mins a day, try running 5 or 5.5mph instead.

I'm not a registered nutritionist or anything, but I did take a nutrition course in university that gave some insight into which energy stores the body uses for what intensity of exercise. Regardless, the body WILL lose weight when working out (assuming you are eating at deficit), but whether the body is burning fat or muscle depends on heart rate. That is why people often lose body fat weight AND lean body mass (muscle). I'll quote a chapter from the textbook.

Brown, Judith E, (2011). Nutrition Now. P. 27-6:

"When we're inactive, fat supplies between 85 and 90% of the total amount of energy needed by muscles. The rest is provided by glucose (about 10%) and amino acids (5%). Fat is also the primary source of fuel for low-to-moderate intensity such as walking, jogging, long-distance running, aerobic dance and swimming. Oxygen is required to convert fat into energy. That makes activities of low-to-moderate intensity "aerobic" or "oxygen requiring." Consequently, fat-burning, oxygen-requiring exercises are the type used to increase aerobic fitness.

"High-intensity, short-duration activities like spiking a volleyball, running down a deep fly ball, or sprinting down the block to catch a bus are fueled primarily by glucose. Our supply of glucose for intense activities comes principally from glycogen, the storage form of glucose. Glycogen is stored in muscles and the liver and can be rapidly converted to glucose when needed by working muscles. The conversion of glucose to energy for intense activity doesn't require oxygen (it's anaerobic)."

Anatreptic

I use the Cross-Trainer, Stair Master (escalator, not paddle style), and the bike machine. I don't run because I have a back issue my chiropractor is trying to correct and exercises with high impact hurt me. I also use a sauna after I work out for 20 minutes, because it makes me feel spectacular afterwards. I agree with your quote about using the glucose, but there is one problem with it. "High-intensity, short-duration". I am not at a short duration. All the glucose theoretically should be burned off within the first 10-15 minutes. I guess I am having trouble drawing the line between optimum and too hard. Because the "optimum" level of exertion makes me feel like I'm not burning enough calories or working hard enough to lose weight.

mmapags

I use the Cross-Trainer, Stair Master (escalator, not paddle style), and the bike machine. I don't run because I have a back issue my chiropractor is trying to correct and exercises with high impact hurt me. I also use a sauna after I work out for 20 minutes, because it makes me feel spectacular afterwards. I agree with your quote about using the glucose, but there is one problem with it. "High-intensity, short-duration". I am not at a short duration. All the glucose theoretically should be burned off within the first 10-15 minutes. I guess I am having trouble drawing the line between optimum and too hard. Because the "optimum" level of exertion makes me feel like I'm not burning enough calories or working hard enough to lose weight.

It makes not difference whether you are burning muscle glycogen or not. Exercise is for health and creating calorie deficit resulting in overall lipolysis (fat oxidation). What fuel substrate you are burning during exercise is imaterial for the most part. My bigger concern is that you are doing all cardio 6 days per week at high intensity and no resistance training.

It's 2 concerns actually. All that cardio can cause a fairly high level of cortisol, a stress hormone which will inhibit fat loss. The second is you will be losing lean mass at a fairly alarming rate as a % of your total loss. The idea is to lose fat and retain lean body mass for optimum health. I'd cut back the cardio and add in some resistance training. I'd probably also take total days working out down to 5 with 2 rest days where I did nothing more that a walk.