Here are a few more details.

This distribution of Calories, with a reasonable breakfast, also helps minimize the risk of a "within-day energy deficiency". The findings in the original study suggest a negative metabolic effect with intra day Caloric imbalances even when the total Caloric input for a full 24 hour period meet your calculated needs..

That study documents "..a significant correlation between the largest single-hour calorie deficits and hormonal disturbances like lower testosterone and higher cortisol." The question is whether that is really a bad thing.

Although studies show animals subjected to fasting and semi starvation diets live longer which may be a good thing in the long run, it is not a successful strategy for an athlete-in-training who needs to keep their body's repair processes at peak efficiency.

If you want to compete at your best, you need to train at your best which includes regular interval training. So anything that limits your interval (or HIIT) sessions is harmful to achieving that goal. The argument is similar to the logic used by athletes who intend to compete at high altitude but need to train at lower altitudes to maximize their ability to stress the cardiovascular system.

There is an ongoing argument as to whether depleting your muscles of glycogen up-regulates fat metabolism which then "forces" the body to improve pathways for fat metabolism. Even if there was proof of this happening (and if there is it is a small improvement) I would suggest that the benefits of limiting interval training as well as the metabolic stresses involved (such as impairing your body's reparative processes) outweigh any advantages from this approach.

The bottom line is that I see few if any downsides to moving a higher percentage of Calories earlier into the day, and only upside benefits.

A recent Dr. Mirkin blog claimed that " Eating Breakfast Helps You Move Faster and Exercise Longer". Although a poor diet might slow you down, as I suggested above, I think the idea that eating a good breakfast will actually add to your speed are an unsupported claim.

First, the complete article that he references.

This is an esoteric study dealing with glucose, insulin responses, and exercise, which I interpret as intended to help design strategies to control blood sugars, not improve exercise performance. So a few of Dr. Mirkin's conclusions from applying them to exercise may be a stretch. (Especially for intense exercise as the article clearly states that their exercise protocol was at 50% maximum potential power levels.)

A few blog comments:

• "you cannot do a substantial intense workout after fasting." I don't believe that is true in all cases. If you have been on a prolonged fast to the point of total body glycogen depletion this is a TRUE statement. You will have depleted your glycogen stores by the fast and only have fat for a muscle energy source. But if you have been eating a normal diet, and just skipped a breakfast, you should have adequate energy stores, and it is not true for short periods of exercise. Even without breakfast, you will still have plenty of stored glycogen (sugar) and be able to use it as a muscle energy source to exercise at your maximum (100% VO2max) until they are exhausted.

• "Since carbohydrates require less oxygen than fats do to power your muscles, you go faster over distance with the greater percentage of carbohydrates your muscles use for energy." This is a true statement. At 100% VO2max you are running on carbohydrates alone as a fuel. Run out of carbohydrate (glycogen) reserves and you cannot maintain a pace much above 50% VO2max.

• "Eating breakfast before a workout helps you process the sugar in your after-work out meal faster, which will help you recover faster." My feeling is that this is still to be proven, Although there may be a slight change in post exercise glucose movement out of the blood and into muscle, if you eat a post exercise meal high in carbohydrates, this is probably a statistical difference, not a practical one.

• "..athletes in all competitions lasting more than 50 minutes should take a source of sugar during their events, or they are at risk for suddenly passing out from low blood sugar levels." This will happen, but after 1 -2 hours, not 50 minutes. On a normal diet the liver will store roughly 100–120 grams of glycogen and skeletal muscle another 400 grams. So let's say that is 500 grams of glycogen. AT 4 Calories per gram, that is the equivalent of 2000 calories. If you are cycling at a brisk pace of 16 - 18 mph you will use about 1000 calories per hour and should be able to ride for about 2 hours before bonking (which is just about how long it takes to run 18 miles, in Dr. Mirkin's blog example, before you hit the wall.)

• If you are on a normal diet, any calories taken before riding will supplement your internal 2000 calories of glycogen and you will be able to ride further before you bonk.

• But there is a placebo effect associated with eating - which suggests that starting a ride hungry could be a negative in your overall performance (even with adequate glycogen stores).

  Another example of an eating related placebo effect is this study of using a carbohydrate mouthwash. Any benefit has to be independent of Calories ingested. It also means that studies on energy drinks need to factor this variable into any conclusions.

• If you eat too close to exercise, GI distress may slow you down. So the 3 - 4 hour pre event meal is good timing.

• Will breakfast make you faster? NO unless you are already glycogen deficient from a prolonged fast or riding daily for 2 or 3 hour rides. Which means you are basically using just your fat stores for energy. But as Dr. Mirkin regularly points out, it is your cardiovascular system that limits your maximum speed, when you have adequate carbohydrate fuel for the muscle contractions. "The limiting factor to how fast you can move over distance is the time it takes to move oxygen into muscles."

  So my suggestion is that if you want to go faster, eat a healthy, balanced diet to maintain adequate glycogen. And keep up those intervals to improve your speed.