Not feeling good :(

I am guessing the same as the above posters. Maybe your weight loss is to fast? How much do you have set to lose a week? If you are only looking to lose 1-2 more pounds you should be aiming for a .5 reduction every week not a 2lb It will allow you to eat more calories and lose still. Also would you be willing to open your diary so we can see your food intake? That will help us give you better advice

Hi Heather, another piece of vital information; what height and weight are you?

Your BMR (Basal Metabolic Rate) looks to be just over 1200 per day based on your height & weight, which means that that is the absolute bare minimum you should eat per day to support your basic body functions. It's what your body would still burn if you didn't move a muscle for 24 hours (heart, brain, nervous system, etc).

From what you're describing as your training levels on the bike you're also probably massively underestimating your calorie burns. At your weight a burn of 400 calories in an hour works out to an approximate average speed 12-14 mph. I've got a feeling if you're training for competitive cycling you could easily be averaging 16-20 mph which would be more like 700 calories burned per hour.

The bottom line is that you're cutting into the calories that your body needs to maintain basic functions. If you're having trouble with the amounts of food involved in eating more try increasing your nutritionally dense foods with healthy fats, such as nuts, peanut butter, avocado, full fat dairy, etc. Your macro split looks fine, you just need more food.

While it's possible this could be a dietary issue, can I add another quite simple suggestion?

Do you think it's possible you're coming down with a cold?

Because what you described feeling "today" is very much how I feel every time I get a cold!

Even taking into account the inaccuracies of such a simple estimate, and the undoubted increases in your efficiency with years of training, 400 seems extremely low, given that at 19 mph the baseline estimated burn is 900 per hour. Have you got any heart rate or power/Wattage metrics for the cycling?

Here's an interesting article on cycling calorie burns and calculations/estimates: http://home.trainingpeaks.com/blog/article/how-accurate-is-that-calorie-reading

I'd suggest starting by upping your base to 1300 (still a 15% deficit to an inactive TDEE) and your cycling calories to 500 per hour. Give it a few weeks and see what the overall trend is. I'd also take care to try and get close to all your macros targets, as you need all three to fuel & repair in training. Your primary goal should be your training and keeping fit and able for it, with slow steady weight loss coming in second place. Otherwise it all becomes quickly unsustainable.

I've opened my diary- didn't realise it was shut

I have it set to 1lb a week. I seem to be losing about that. It gives me 1200 base whether I set it to 0.5lb week or 2lb week though so doesn't seem to make a difference!

My carb percentage is already really high coz of the training, if I up it any more I won't get any protein in. I just don't know what to do.

Please Check this again. MFP gives me 1370 base calories when I setup my account to weigh 129 lbs and .5 lb per week loss. That said, using the fixed daily calorie method could help you if you'd prefer to avoid tracking exercise calories. If not I would definitely increase the base calories to around 1400

I don't have specific numbers to back up my claim, but you're just too small. Your initial 400 calorie number for net calories burned is not too far off the mark IMO. For me, going full pelt in one of my classes I'm maxing out at around 550 calories (and losing at the expected rate). Your intensity may be up there but in addition your body is smaller.

I would definitely up base calories to 1400

The exercise I probably wouldn't go more than 500

1400 would put you in a good position to work from, and is still in deficit without taking any exercise into account other than normal 'sedentary' daily activities. Most likely you've got a higher lean muscle mass percentage than most and your metabolism is higher than average, so 1400 is safe.

I'd still suggest a higher per hour figure on your cycling burns too. You need to keep fueled.

I typically don't feel all that lethargic when I overdo my calorie deficit, just really hungry.

I'd agree that 400 calories per hour is an underestimation based on your weight. If you are trying to net 1200/day, that does not leave much wiggle room for error.

I'd up your calorie level and see how you feel. You can do it slowly in increments and observe effects on the scale.

Not sure where you are getting your number but they are not even close to what I get with various calculators:
129 pound rider, 18 pound bike
540 C / hr @ 18mph
550 C / hr @ 19 mph
1432 C/ hour @ 27 which is 398 watts, in a peloton she is not burning this in spite of the speed unless she is leading the entire time which is doubtful. If she is in a breakaway unless she is solo she is also not burning that in an hour unless she is leading the whole time and frankly cycling just does not work that way.

You must have access to better calculators than I could find. Any chance of sharing the link(s) if they're online? Always looking for better sources of information.

Then there is the fact that the more one cycles the more efficient they become at cycling burning even less Calories than before.

That's not really true; the more one cycles, the better the muscles get at recruiting fibers and the better the fibers get at contracting, as mitochondria and vascularization increase. But that simply means that you can use more energy in the same amount of time, i.e. you can put out more power.

Bikecalculator.com, btw, estimates that a 129-lb. cyclist on a 20-lb. bike riding at 19 mph on flat terrain with no wind, on the hoods, with clinchers, will burn 608 calories per hour. On aerobars that drops to 519 cal./hour.

For what it's worth, the numbers are not much different for a much heavier combo, because the faster you go, the more wind resistance is the main force to overcome. I'm a 160-lb. rider, and my usual bike weighs 35 lb. (25.6 lb. bike with fenders and front rack, but add 9.5 lb. of water bottles, food, and tools for an all-day ride or a brevet.) Bikecalculator estimates that I would need 639 calories per hour to do 19 mph on flat terrain on the hoods, and 548 with aerobars (not that I have them).

On the other hand, if we were evenly matched on the flats, the lighter cyclist would drop me in a flash when we came to a serious hill. It's really striking how much faster I am on hills than I was at 210 lb....

Heather: I think you should try eating a little more per hour of training; you're almost certainly burning more like 500-550 calories/hour at your training pace, since you're not drafting, and even more during races. I don't race, but I do club rides and endurance events up to 200 km, and I find that my Garmin Edge 800's calorie estimates agree fairly well with my actual weight loss results; it, in turn, isn't too far off of bikecalculator's estimates.

Congrats on your PR!