Fasted training has been a debate in cycling for fifteen years — much of it heat, very little of it light. The Van Proeyen 2011 paper showed real adaptation in fat oxidation and intramuscular triglyceride use when riders trained fasted in base. The follow-up Burke 'train low, race high' literature confirmed the basic mechanism. Both papers also flagged the cost: fasted high-intensity work compromises adaptation, and chronic under-fuelling produces the energy-availability problems behind RED-S. The honest answer sits in the middle of those two findings.
What fasted training is good for: a short, easy aerobic ride done before breakfast, in base season, when the body has time to absorb a low-intensity stimulus without competing demands. 60-90 minutes, conversational, zone 2. The metabolic signal is real — slightly improved fat oxidation and a small mitochondrial bump — and the cost is contained. Dr David Dunne's framing on the podcast is the cleanest summary: 'A periodised tool, not a default. Used carefully, in the right phase, on the right rider.'
What it isn't good for: anything that matters. Fasted threshold work, fasted VO2max, fasted long rides over 90 minutes — these reliably tank the session, increase muscle-protein breakdown, and steal recovery from whatever you do next. Anthony has been explicit on the podcast: 'You end up bonking 60k from home and end up absolutely hating your life — that's not training, that's a withdrawal symptom dressed up as discipline.' The sessions that produce FTP gain need to be fully fuelled. Always.
The other red flag is using fasted training as a weight-loss tactic. The cycling research is unambiguous on this: training under-fuelled to lose weight reliably costs FTP, immune function, and (in women) menstrual function. The RED-S literature (relative energy deficiency in sport) is now the dominant frame for understanding what goes wrong. The Roadman position, anchored in those studies and in the published Lorang/Wakefield comments on World Tour fuelling, is direct: fuel the work, take the deficit on rest days, and don't try to shortcut body composition by riding hungry.
Practical pattern that works for amateurs: in base phase, one or two short pre-breakfast zone 2 rides a week, with a high-protein breakfast immediately after. Don't stack fasted with hard sessions. Once you're in build or peak phases, drop them — every ride needs to be fuelled. Female cyclists, particularly perimenopausal masters, should treat fasted training with extra caution; the published literature on hormonal disruption from low energy availability is clear.