Losing body fat is a bonus side effect of endurance sports, right?
Not wholly true.
If you are doing the right things, then the training and racing CAN lead to decreased body fat and bring out those six pack abs you always knew you had hiding under that last bit of belly fat.
But, losing that last bit of body fat is a tedious endeavor, because your body really likes to hang on to its fat.
Intensity - The name of the game is burning more calories than you are taking in. If you think you're handling the food side, then look at your workouts. If you're not getting into zone two aerobic work, the best fat burning zone, then chances are that you are not going to do much change with your current workouts. Consider longer workouts (run, bike) in the middle zone two range to burn that fat.
Nutrition - Crap in equals crap out... literally and figuratively. If you are enjoying Chipotle and Cold Stone and still burning more calories than taking in, it's time to look at the quality of the calories you are taking in. If you aren't supplying your body with the right building blocks, then the calories will go to places they aren't meant to. Think of it as eating to live, and not living to eat. Training for long course triathlons is not a license to eat crap calories.
Stress and Cortisol - If you are stressed from work, home or other areas, you're body will counteract that by producing cortisol and wreak all kinds of havoc on trying to get rid of fat. Find ways to relieve the stress, and your body will be more open to and willing to work correctly in letting go of the excess chub.
Recovery - If you are a workout machine and you are sacrificing sleep and recovery in the pursuit of fat loss and getting rid of that last little bit of belly fat, then you're doing yourself a disservice. Go back to looking at food intake and workout intensity and adjust those before losing out on at least 8 hours of sleep a night. If you're body is not properly recovered, it won't function optimally and losing body fat will be the least of your problems.
Hormones - Women AND men, hormones can run rampant. Hyperthyroidism is just one condition where the body produces too much of a hormone that hinders weight loss and promotes weigh gain. Make sure you have checked with your doctor and ran some simple tests to rule out any hormone conditions.
Genetics - Sometimes your body just has a natural set point. You may have to go to extremes to lose that last little bit that your body just doesn't want to give up. It may require a herculean effort to cut out the crap foods and eat clean and workout on a religious level. If you have to reach a lifestyle that is unattainable for a long term period, it may be time to re-evaluate what you are willing to live with. If you have to workout 10 hours a week and cut down to 1500 calories a day to get that last bit of fat off, that may not be realistic. Have some metabolic testing done to see how efficient your body is and adjust your workouts accordingly.