ABOUT THE AUTHOR: Peter Miller holds a Master’s degree in Sports and Exercise Science from the University of Chester and an ISSN Diploma in Sports Nutrition from Middlesex University. He has supported 20 world champions across UFC, ONE Championship, PFL, Cage Warriors, WBC Muay Thai and Olympic boxing.
HEALTH AND SAFETY: Weight-making and dehydration carry real risks. This article is educational, not a water-cut protocol. Any athlete planning weight loss, dehydration, or post-weigh-in refuelling should work with an appropriately qualified practitioner and follow their promotion’s medical rules.
TL;DR / Direct answer
Jonathan Haggerty’s bantamweight transformation was supported by a fully tailored fight camp nutrition strategy built around his training schedule and ONE Championship weight requirements. Peter Miller managed Haggerty’s weight-making, hydration and performance fuelling, helping him make weight safely and compete at world-title level across Muay Thai and kickboxing. His exact meals and private targets are not published because those details are individual to the athlete and event. [1][2]
Key points from the infographic
- Build a tailored nutrition plan around the full fight camp, not a generic copy-and-paste diet.
- Manage body mass gradually while protecting the hard sessions that build performance.
- Fuel training and recovery consistently as the competition date approaches.
- Treat the weigh-in and post-weigh-in refuelling as part of performance preparation.
- Do not copy another fighter’s food amounts, fluid targets or weight-cut protocol.
Contents
- The verified Jonathan Haggerty bantamweight case study
- Why a Jonathan Haggerty diet is not a downloadable meal plan
- Muay Thai diet and fight camp nutrition: the working framework
- What should fighters eat after a weigh-in?
- What competitive Thai boxers can take from this case study
- Related Condition Nutrition guides
- Condition Nutrition fight camp support
- Frequently asked questions
- References
The verified Jonathan Haggerty bantamweight case study
Jonathan Haggerty is a ONE Championship world champion in Muay Thai and kickboxing. Condition Nutrition confirms that Peter Miller provided Haggerty with full fight-camp nutrition support at ONE Championship, including a tailored approach to weight-making, hydration and performance fuelling. Condition Nutrition states that this support helped him make weight safely and fuel peak performance in his ONE Muay Thai and kickboxing world-title wins. [1]
This is the important distinction behind the phrase “bantamweight transformation”. It is not a claim that one public diet turned Jonathan into a champion. It is the documented shift from a fighter managing the demands of a weight-category sport to a fighter supported by a plan that connected camp nutrition, body-mass management, fight week and competition performance.
Why a Jonathan Haggerty diet is not a downloadable meal plan
Publishing exact food amounts, fluid targets or a water-cut schedule would be irresponsible. Those decisions depend on the athlete’s body mass, medical history, food tolerance, training schedule, travel, official weigh-in timing and the time between the scales and the fight. The International Society of Sports Nutrition states that the combat sport, fight-camp length and time between weigh-in and competition all affect nutrition and weight-cut strategy. [2]
For that reason, this Jonathan Haggerty diet case study explains the decision-making, not private numbers. A useful Muay Thai diet should help a fighter complete hard training, move towards the required weight class in time, and arrive at fight week with fewer last-minute decisions. It should never be treated as a generic crash diet.
Muay Thai diet and fight camp nutrition: the working framework
A Thai boxer diet has to serve more than one job. It must support training and recovery while body mass is being managed for a set date. Good fight camp nutrition therefore starts early enough to avoid leaving the whole job to dehydration in the final days. The ACSM consensus on weight-category sports supports a planned, long-term approach to body-mass management rather than unhealthy weight-loss practices. [3]
| Stage | What the nutrition plan must solve |
| Early fight camp | Set a realistic body-mass direction while keeping enough energy available for the work that builds the fight. |
| Hard training weeks | Match food and fluid intake to the changing training load, not to a fixed online meal plan. |
| Final preparation | Reduce uncertainty by confirming the target, travel, weigh-in rules, food access and the individual response to the plan. |
| Fight week | Use an individual strategy that protects health and gives enough time and structure for recovery after the weigh-in. |
Table note: This is an educational planning framework, not a prescription. The exact strategy must be individualised. [2][3]
This is what makes the case study useful to a competitive fighter. The lesson is not to copy Jonathan Haggerty’s private meals. The lesson is to stop treating nutrition as something added to camp in the final week. A well-chosen nutrition strategy can support training, recovery and competition preparation, but the amounts and timing must fit the athlete and the event. [4]
Planned fight camp nutrition versus a last-minute weight cut
| Area | Planned across fight camp | Left until fight week |
| Body mass | Progress is monitored against the competition date. | More scale weight may be left to lose at short notice. |
| Training fuel | Food is adjusted around the changing training load. | Aggressive restriction can compromise hard sessions. |
| Fight week | Travel, food access, weigh-in rules and recovery are planned. | More decisions are made under pressure. |
| After weigh-in | Familiar fluids and foods are selected and tested in advance. | The fighter may improvise when the gut is already stressed. |
Table note: This comparison explains the planning principle shown by the case study. It is not a weight-cut protocol. [2][3]
What should fighters eat after a weigh-in?
Fight week nutrition is where the risks become clearer. Rapid weight loss and dehydration can place strain on the body and can impair aspects of physical and cognitive function. The correct approach is not “the hardest cut possible”. It is the safest workable approach for that individual, with professional oversight and enough time to recover before competition. [2][3]
After a weigh-in, a fighter generally needs to begin replacing fluid and sodium, restore carbohydrate availability and then return to familiar, easy-to-digest meals. The exact amounts and timing depend on the athlete, the weight-making method and the time until competition, so this is a recovery framework rather than Jonathan Haggerty’s private plan. [2][7][8]
- Start with a familiar oral rehydration or electrolyte drink rather than relying only on large volumes of plain water.
- Add familiar, easy-to-digest carbohydrate foods to begin restoring energy used during the cut.
- Build into small meals containing carbohydrate and lean protein as the athlete’s gut tolerates them.
- Avoid experimenting with unfamiliar foods, very large meals or foods that regularly cause gut problems.
- Agree the sequence before fight week and adjust it to the official weigh-in and competition timetable.
This answers the general question “what to eat after a weigh-in” without presenting a universal meal plan. Fighters who need a detailed sequence should use the dedicated Condition Nutrition rehydration and post-weigh-in guides, then obtain individual support for any meaningful weight cut. [7][8]
What competitive Thai boxers can take from this case study
- Make body-mass management part of the full fight camp, not a last-minute punishment.
- Use a Muay Thai nutrition plan that changes with training demands, travel and the competition calendar.
- Do not copy another fighter’s diet, water targets or post-weigh-in meal plan.
- Treat the weigh-in and the period after it as part of performance preparation, not as separate problems.
- Use qualified, individual support when a weight cut, dehydration or refuelling strategy is involved.
Condition Nutrition fight camp support
Condition Nutrition provides elite fight-camp support, elite fight-week support and VIP pro support. The service is built around the same principle shown in this case study: a fighter needs a tailored plan for the full camp, not a generic diet handed over at the end. Support can include a periodised nutrition plan, a fight-week strategy, post-weigh-in refuelling planning and ongoing adjustments based on the athlete’s competition timeline. [5][6]
Fight Camp Nutrition Plans: https://conditionnutrition.org/fight-camp-nutrition-plans/
Weight Cutting, Fight Week and Fight Camp Nutrition: https://conditionnutrition.org/weight-cutting-fight-week-fight-camp-nutrition/
Related Condition Nutrition guides
These supporting articles cover the practical questions that sit outside Jonathan Haggerty’s private case-study details:
Muay Thai Fight Week Diet: Simple Plan and Food List: https://conditionnutrition.org/muay-thai-fight-week-diet/
Rehydration After Weigh-In: 24-Hour Plan: https://conditionnutrition.org/rehydration-after-weigh-in-24-hour-plan/
What Not to Eat After Weigh-In: Avoid Gut Problems: https://conditionnutrition.org/what-not-eat-after-weigh-in-avoid-gut-problems/
Cutting Weight Without Losing Power: https://conditionnutrition.org/cutting-weight-without-losing-power/
Frequently asked questions
What is Jonathan Haggerty’s diet?
Jonathan Haggerty followed a tailored fight camp nutrition plan prepared by Peter Miller for his ONE Championship weight-making, hydration and performance fuelling. The plan supported his Muay Thai and kickboxing world-title success. Exact meals and targets remain private because they are individual to each athlete and event. [1][2]
How did Jonathan Haggerty make bantamweight?
Condition Nutrition states that Peter Miller’s full fight-camp nutrition support helped Jonathan Haggerty make weight safely and fuel peak performance during his ONE Championship title-winning run. Exact body-mass, food and hydration targets are not published because they are individual and event-specific. [1][2]
What is the best Muay Thai diet for fight camp?
The best Muay Thai diet is the one matched to the fighter’s training load, body-mass target, competition date and food tolerance. It should be planned across the whole fight camp rather than copied from another athlete or saved for fight week. [2][4]
What should a Thai boxer eat after weigh in?
After a weigh-in, a Thai boxer generally needs fluid and sodium first, followed by familiar, easy-to-digest carbohydrate foods and then small meals containing carbohydrate and lean protein. Exact amounts and timing depend on the athlete, the cut and the time until competition, so the sequence should be planned before fight week with appropriate professional support. [2][7][8]
References
- Condition Nutrition. “About Us: Building Champions Through Nutrition.” Accessed 12 July 2026.: https://conditionnutrition.org/about-us-condition-nutrition/
- Ricci AA, Evans C, Stull C, et al. International Society of Sports Nutrition position stand: nutrition and weight cut strategies for mixed martial arts and other combat sports. Journal of the International Society of Sports Nutrition. 2025;22(1):2467909. doi:10.1080/15502783.2025.2467909.: https://doi.org/10.1080/15502783.2025.2467909
- Burke LM, Slater GJ, Matthews JJ, Langan-Evans C, Horswill CA. ACSM Expert Consensus Statement on Weight Loss in Weight-Category Sports. Current Sports Medicine Reports. 2021;20(4):199-217. doi:10.1249/JSR.0000000000000831. PMID:33790193.: https://doi.org/10.1249/JSR.0000000000000831
- Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Journal of the Academy of Nutrition and Dietetics. 2016;116(3):501-528. doi:10.1016/j.jand.2015.12.006. PMID:26891166.: https://doi.org/10.1016/j.jand.2015.12.006
- Condition Nutrition. “Fight Camp Nutrition Plans.” Accessed 12 July 2026.: https://conditionnutrition.org/fight-camp-nutrition-plans/
- Condition Nutrition. “Weight Cutting, Fight Week and Fight Camp Nutrition.” Accessed 12 July 2026.: https://conditionnutrition.org/weight-cutting-fight-week-fight-camp-nutrition/
- Condition Nutrition. “Rehydration After Weigh-In: 24-Hour Step-by-Step Plan.” Accessed 12 July 2026.: https://conditionnutrition.org/rehydration-after-weigh-in-24-hour-plan/
- Condition Nutrition. “What Not to Eat After Weigh-In: Avoid Gut Problems.” Accessed 12 July 2026.: https://conditionnutrition.org/what-not-eat-after-weigh-in-avoid-gut-problems/
About Peter Miller
Peter Miller holds a Master’s degree in Sports and Exercise Science from the University of Chester and an ISSN Diploma in Sports Nutrition from Middlesex University. He has supported 20 world champions across UFC, ONE Championship, PFL, Cage Warriors, WBC Muay Thai and Olympic boxing. His work with fighters includes full fight-camp nutrition, fight-week planning, weight-making and post-weigh-in refuelling support.