On the one hand, I can't put myself in your shoes because at 21, I probably weighed about 145 pounds and now, almost 30 years later, I still weigh about 145 pounds. I don't recall the last time the scale put me over 150 but long summer runs will put me under 140 due to dehydration. I've never had to count calories but I also don't usually feel any compulsion to binge on stuff, whether it's ice cream, soft drinks, or beers.

Having said that, I think the important thing with diet is to get enough nutrition from a variety of natural sources that you're not shorting yourself on critical trace minerals and vitamins, especially the fat-soluble ones. If you're trying to lose a significant amount of weight then it's going to take some time to do that in a way that's sustainable in the long term especially while you're maintaining a heavy training load. A reasonable target is one pound of weight loss per week.

Suppose you run 15 hours/week, logging 8 miles per hour... in 120 miles you'd burn 14400 calories, making a completely wild-ass guess of 120 calories per mile (for whatever your body weight is - one rule of thumb is 100 cal/mile for a 150 pound man). That many calories is equivalent to the energy contained in about four pounds of body fat. But, nothing says that the fuel for your runs is going to come from that, especially if other fuels are more readily available to your muscles. Another thing is that running is about the most time efficient way of burning calories there is, unless you do multi-hour sets of riding at near-FTP levels of intensity.

If you're logging calories, you may be overestimating your caloric output while underestimating the intake... The food side of weight loss is far more critical in determining whether you gain or lose than the exercise side.

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Less is more.

This will induce a religious level debate, but hopefully some simple guidelines will get us far. :)

1.) It really is as simple as "calories in," "calories out". So you're understanding is correct.
1.a.) "Calories in" is pretty darn simple, although there might be some small amount of up/down regulation of absorption.
1.b) "Calories out" may be modulated by metabolics.
1.c) 1.a and 1.b are secondary effects that confound 1 by itself, but, really 1 rules the day.

2.) Controlling "calories in," "calories out" on the lifestyle side is a bit tougher, as you're finding out. Are you sabotaging yourself? To a small degree, yes. Is it ultimately going to ruin you? Probably not, and, even more so, a bit of "junk" along the way might be helping with overall, long-term dietary changes (done reasonably at least, we humans are terrible at self control, so a bit of junk here and there may/hopefully mean that you achieve long-term compliance).
3.) Overall, long-term dietary behaviors are king/queen. While you are presently concerned with how much you weigh in 6 months, I'd happily argue that you should be concerned with how much you weigh in 5 years. So what if you drop 25 pounds in 6 months and it takes another 6 months to lose the last 10 lbs? You may hit hang-ups, your body may fight you tooth and nail to drop the last few pounds, or you realize that dieting is killing your training. Actually...
4.) Don't focus on the weight. Focus on the lifestyle/behavior and let the weight fall where it may.
4.a) I wasn't kidding about the not focusing on the weight.
4.b) Really. Eyes on the long-term prize.
5.) You can't really exercise your way out of excess weight--as working out makes you hungry. :) It's much more about regulating what goes in. That said, exercise is great, great, great unto itself for various reason, and will help you better achieve 2-4 (Psychologically as much as physically).

Good luck! Seriously, though, focus on building good behavior and let weight take its course. Put your daily weight into a spreadsheet and apply a 2-week rolling average to it. Follow trends, not noise.

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The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock

Ok awesome stuff. It is a gigantic challenge to not want immediate results, which I guess is the nature of being an American. Instant gratification always. So far, and it's a small sample size, I feel like I'm more likely to make better decisions most of the time by allowing myself to make less than perfect decisions some of the time. I use an HRM for all of my workouts except swims. I generally will follow my 910 on kcal burn for all three workouts, with run/bike being driven by HRM. I feel 90% confident that diet log is accurate as I measure, almost obsessively so, everything. On my longer workout days, say long run 12mi, the extra 2500 cal burn I pick up I struggle to reabsorb in food, so I don't think extreme over eating is an issue. I also might want to believe that bc of the new muscle mass I am building, especially in the pool and from power training on the bike, that weight on a scale might not be as accurate in the short run. The whole muscle weighs more than fat thing. I guess the real test on how well this is all working will be quarterly to see what progress looks like and weight in combo with bf%.

Derf hit the nail on the head. You control what you eat. You control how much you exercise. You don't control the amount of energy "burned" while sleeping, working, etc etc etc. A physiology lab can measure that, but it's a bit different for all of us.

So really, it's all just a bunch of guess work, because without some legit scientific testing there's really no way to know what your base caloric intake should be. It's nice that calculators will say a person of x age weighing x lbs working a certain activity level should consumer x calories as a base, but if I'm understanding what you guys are saying, that base number could be off drastically.

Is there also truth in too few calories? I totally understand the performance impacts, but we're talking strictly fat loss here.

I wouldn't trust your HRM, muscle mass gain, nor any assumptions you make about reabsorption to be remotely accurate. Those are things that can be determined in lab, but tend to be less helpful in practice. Pay attention to behaviors on a daily basis (good on you and that food log), and watch trends. There's a huge time-averaging thing happening on weight loss that makes day-to-day look rather noisy.

Set a general trend of average dietary intake. Be honest about it by looking at your average intake over the past month. Your hard exercise days you should assume you'll be a bit over that target, and your lighter days a bit under. (Another good place to do a 1-week moving average is on calorie consumption!) If that average dietary intake isn't losing you weight (or, perhaps better observed as body composition), then maybe knock it down by 50-100 calories per day and see what happens in the next couple weeks thereafter.

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The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock

That's helpful too. The float that I experience on the scale watching the number daily can be a bit frustrating. But over the month 5lb loss. Hoping to see similar results in month 2. But trying not to get discouraged with that float can be a bit of a challenge. I will def look at monthly averages though. Thanks!

It is a bunch of guess work to a degree. BUT if you are consistent in your training and eating you will find that sweet spot where you can lose 1-2 lbs per week. Be honest and accurate about what's going in and keep up the working out. Quality of food is important and I believe more so when you're at a deficit. Having a good ratio of fat to protein to carbs will stave off binging and eating nutrient rich food keeps the body healthy. A little ice cream once in a while isn't bad but I can't keep it in the house. I eat frozen yogurt bars instead.

I lost 80 lbs that way while at the same time quitting smoking and have been able to keep it off.

That's awesome! Congrats and good stuff! I quit smoking 14 months ago after pack-a-day habit for 10+years. This weight loss and transition into becoming an endurance athlete is kind of the last step in my transformation from someone I hated to someone I love. Sorry to be cheesy, but with smoking and everything in life, I've learned if the goal isn't important to you, you are not likely to achieve it.

Brings up another interesting question. Is there a certain formula for macros that would be considered "best" for a triathlete? We all hear to eat carbs, but the reality is if you have an alternative fuel source (fat) are carbs really necessary? I get fruits and whole grains, I'm italian, no chance i'm totally skipping on bread for eternity though. Protein heavy is cool too, but to a degree I can imagine that a "Weight lifter" diet of 1-2g/lb of protein is necessary or even healthy for a triathlete. Fats are good, natural oils, avocados, etc but again, is there a magic split? 40-30-30 protein/fat/carb? Or is concerning yourself with that too much just asking for burnout? Because the reality is that "diet"/weightloss/training needs to be maintainable. Anyone can do atkins for a month or two. But in the long run, the 5 year plan, should you be concerning yourself with macros?

I imagine counting calories is a way to lose weight but I don't see this as sustainable. I believe changing the way you eat could solve all the issues and then you don't have to worry about tracking calories which you will most certainly get wrong one way or the other.

There are multiple ways to do this (high fat diet, paleo, etc.) but for me it is easiest to eat as natural as possible. That means avoiding processed foods almost all the time and for sure sugars. I think Phil Maffetone did a write up on this but try and go 2 weeks and not eat any sugars and processed foods (breads, pastas,etc). See how you feel and if you are "naturally" losing weight. If you find some workouts a little flat supplement just before, during, or after the workout but actually you are probably OK if you just back off in intensity.

For me there would be no way I could count calories so this is much more sustainable and healthier.

It's good to allow yourself "less than perfect" decisions; if you don't then you've basically predetermined that you're going to "fail" sooner or later. An indulgence now and then isn't going to break anything and can give you a morale boost as long as you don't somehow feel the need to punish yourself afterward.

But you're making a huge overestimate on running calorie burn there. Even at 200 pounds (an assumption because you haven't said where you're at), 12 miles running should net you at MOST 1800 kcal burned. Cycling, without a power meter, will give you grossly inaccurate calorie burn estimates, HRM or not. Because it's a supported exercise, and you can coast and draft, the distance you cover and the speed you go don't reflect the energy burned. You can do it based on RPE and time... but you need to have a good baseline for that to begin with.

As you noted in another post, a person's base metabolic rate and metabolic efficiency during exercise make a substantial difference in the number of calories burned. So in the end, the only true measure of whether or not you're ahead or behind the calorie curve, is what your scale says on a week to week or month to month basis. But persistence pays off... it does benefit you to log your weight on a daily basis so that you can track trends over time and average out the minor fluctuations due to hydration or whatever else.

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Less is more.

I am currently 240. You wouldn't know it looking at me, I carry a ton of muscle and am very broad. I have tested 22% bf. 12 mi run, 2300 is what Garmin tells me. I do use the kcal burn from TrainerRoad, which is power based, so my cycling stuff should be pretty accurate. Meant to clarify that when I said I used HRM. It's in conjunction with TR, so is -power based. Hour in zone 2 nets me around a 400 kcal burn. Swim calories are always nominal. 700-900 for hour swim (actual swim time, not time in pool).

You're correct. After a deficit of about 3500 calories, you'll lose a pound. When I need to lose weight, I try to eat 1500 calories plus however many calories I exercise. This will cause me to lose a pound per week, which is reasonable for me.

Keep in mind that if you weigh every day (and you should, to keep calories and weight in your mental forefront), you'll vary a couple of pounds based on the amount of water and food currently in your body. This is true even if you weigh first thing in the morning.

And, knowing that a milkshake (or whatever) will cost you an hour on the bike will induce better eating habits.

OK... but: If you want to lose weight, give yourself a 10% deduction on any estimate of calories burned, rather than a 10% credit. So if your 910 says 2300 on a 12 mile run, log 2100 rather than 2500; if TrainerRoad says 800 for an hour on the bike (are you using Virtual Power?), credit yourself 720.

Even if/when you have a power meter for cycling, you have to recognize that a rider's metabolic efficiency can make a substantial difference in the true calories expended for a given amount of work done, because if you don't you can end up substantially on the wrong side of the calories in vs. out totals.

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Less is more.

That makes perfect sense

i found the biggest thing about counting calories in for even just a month was it made me realize how bad some foods are in terms of being high in calories.

oh you want that dessert? you can have it but that's all you're eating today unless you spend 3 hours on the bike.

That understanding helps you with the lifestyle change, and makes you far more aware of portion sizes. It's very easy to eat a lot of healthy foods and end up still overeating due to portion mismanagement.

I think that's my goal with the calorie counting. It makes me measure portions and learn the quantities of what you can and can't eat within that restriction.

While counting calories may not be "sustainable" it is a good way to lose the weight and at the same time learn to eat in a way that once you stop counting will keep the weight off. I was a chronic over eater and ate crap. That's how I got to 270. Counting calories helped me learn better more sustainable eating habits. I still eat like crap once I a while. I'm told I have an addictive personality which incidentally lends itself to training 15-20 hours per week too.

sounds familiar.

biggest thing is learning the easy come/easy go risks and how to overcome them.

Big Endian makes some great points: It's better to outright ignore the "calories burned" number and focus on whether, on the whole (which blindly accounts for exercise and metabolics), your average eating habits are inducing a calorie deficit (as evidenced by gradual weight loss).

That's simple. Train a bunch (this will likely balance out over time, and you can only train so much) but don't worry about quantifying calories burned, just measure calories in and weight loss. Apply a big moving average (1-2 weeks) to the latter two. If weight loss isn't happening, you need to drop the calories, as the "in/out" ratio is off.

That said, if using a PM on the bike, the 1 kj = 1kcal is pretty robust. Biking "efficiency" on average sits pretty close to 25%, which cancels the 4.1 kJ per kCal. Still wouldn't try to calculate calories burned over time.

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The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock

Not that you need to do this per se but, if you want to know roughly how many cal/day you're burning at rest, then you could get your resting metabolic rate (RMR) measured. My gym has a machine that does it by putting a nose clamp on your nose, then you sit quietly and breath in and out of a clear plastic hose for 10 minutes. The machine measures how much oxygen is left in your breath vs how much O2 is in the background air around you, and thus determines how much O2 you're using at rest, and calculates your RMR in cal/lb. I had this done a few yrs ago and came out at 14.2 cal/lb or about 2500 cal/day at my typical weight of 176 lbs and height of 6'1". For the past few yrs i've used the 2500 cal/day for my basic intake plus how ever many cal I burn in exercise during the day. Seems to work pretty well for me. It was kind of cool thing to get this info IMO, although I did just fine for years before that measurement, just going off my own estimate of my RMR at 2300-2400.

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"Anyone can be who they want to be IF they have the HUNGER and the DRIVE."

Are we assuming here that one will still eat what is needed add energy for training? I can't imagine you can do 12 hours of training and not remotely compensate for that burn. Wouldn't you risk losing too much to quick or health concerns from under eating for the work your doing?

The far better equation is "estimated calories in vs estimated calories out."

Precise intake and output for normal people is not realistic. "Ballparking" it usually works well. But as others have said, it has to be sustainable.

Certainly, here's an example: Let's say you at 240 lbs have a RMR of about 3000 cal/day, which is prob on the low side but def not overly optimistic if you're at 22% BF. In your daily workouts, you're burning say 1000-1500 cal, so about 4000-4500 total. To lose 1 lb/wk, 3500 cal deficit/7 days = 500 cal/day ==> you should eat 3500 to 4000 cal/day. To be on the safe side, and to maybe lose 1.5 lbs/wk, aim for 3000 to 3500 cal/day, which is still a fair amount of food. Since you're in the habit of measuring what you're eating, shouldn't be too hard:)

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"Anyone can be who they want to be IF they have the HUNGER and the DRIVE."