Matt is joined by Dr David Lipman to discuss one of the newest and most talked-about supplements emerging in elite endurance sport: lactate gels.

Train with Matt Fox:
https://sweatelitecoaching.com/matt-fox/

Sweat Elite Supporters Club:
https://sweatelite.co/supporters-club/

Matt Fox on Instagram:
https://www.instagram.com/mattinglisfox/

Matt Fox on Strava:
https://www.strava.com/athletes/6248359

Contact Matt:
matt@sweatelite.co

Dr David Lipman on Instagram:
https://www.instagram.com/drdavidlipman/

Dr David Lipman's Website:
https://www.drdavidjlipman.com/

The conversation has gained attention around the Tour de France, with companies including From Lab to Field, Enervit and Santa Madre developing lactate-based products. Unlike glucose and fructose, which rely primarily on SGLT1 and GLUT5 transporters in the gut, lactate uses monocarboxylate transporters (MCTs). This potentially provides athletes with another pathway to absorb and utilise energy alongside traditional carbohydrate fueling.

The concept isn't completely new, but delivering meaningful amounts of lactate without creating gastrointestinal or taste problems has historically been difficult. From Lab to Field is developing a patented hydrogel designed to improve lactate delivery and tolerance while producing a less acidic product. Early prototypes have reportedly combined around 5 g of lactate with 40 g of carbohydrate.

There are also interesting possibilities beyond simply providing additional energy. Lactate can be used as fuel by the muscles, heart and brain and also acts as a signalling molecule. Researchers are investigating whether supplementation could influence glycogen replenishment, recovery and metabolic responses during exercise.

There are already some impressive performance claims circulating, including improvements in power output and reductions in fatigue, but the evidence remains preliminary. Much of the exciting data appears to come from research connected to the companies developing the products and still needs independent replication.

One particularly interesting possibility is that lactate supplementation may have different effects below versus above the first lactate threshold. Elite athletes reportedly using lactate alongside very high carbohydrate intakes of around 90-120+ g/h have described positive experiences, but exactly how much additional benefit lactate provides remains uncertain.

The discussion also compares lactate with exogenous ketones, another alternative fuel that has generated significant interest in endurance sport. Ketones have produced mixed performance results, although emerging research suggests potential benefits in areas such as heat tolerance, recovery, altitude exposure, sleep and resilience to heavy training.

Both lactate and ketones may eventually have applications outside sport because of their roles as fuels and signalling molecules, particularly in the brain. Overall, lactate gels represent an exciting new area of endurance nutrition, but they're still at the beginning of the research cycle. The potential is significant, but athletes should distinguish promising early findings from benefits that have been independently and consistently demonstrated.

Episode Chapters:

00:00 Lactate Gel Buzz
00:19 Who's Making Them
01:16 How Lactate Fuels
02:53 Hydrogel Delivery Breakthrough
03:58 Legality and Doping Questions
05:20 Performance Claims and Evidence
06:42 Real World Use and Cost
07:43 Beyond Sport Applications
08:56 Ketones Update and Research
11:25 Personal Ketone Use Cases
12:44 Conflicts and Wrap Up

Jordan Sullivan, The Fight Dietitian, joins Matt to break down performance-focused weight loss, RED-S, marathon fueling and how endurance athletes can get lighter without sacrificing training quality.

Jordan Sullivan / The Fight Dietitian

Website: https://thefightdietitian.com/

Instagram: https://www.instagram.com/the_fightdietitian/

Matt Fox / Sweat Elite

Coaching: https://www.sweatelitecoaching.com/matt-fox/

Instagram: https://www.instagram.com/mattinglisfox/

Strava: https://www.strava.com/athletes/6248359

YouTube: https://www.youtube.com/@SweatElite

Sweat Elite: https://www.sweatelite.co/

Sweat Elite Instagram: https://www.instagram.com/sweatelite/

Contact: matt@sweatelite.co

In this episode, Jordan and Matt dive into one of the most debated topics in endurance sport - losing weight while training hard. Jordan has spent more than a decade working with elite athletes across combat sports, endurance events and other high-performance environments, helping athletes manipulate body composition while maintaining performance.

They discuss RED-S, low energy availability and why the intensity and duration of a calorie deficit matter. Jordan explains why training status is an important part of the equation, how quickly athletes can realistically lose weight, and why Garmin, WHOOP and other wearable calorie estimates should not be treated as exact measurements.

They also explore what happens to muscle during a calorie deficit, the roles of protein and resistance training, and what changes when an already-lean athlete tries to become even lighter. Jordan and Matt discuss Matt's own progression from around 74 kg toward 69 kg, and the longer-term possibility of experimenting closer to 65 kg while trying to determine where further weight loss stops improving marathon performance.

A major part of the conversation focuses on fueling marathon training while losing weight. They discuss periodizing calorie and carbohydrate intake around important sessions, why harder running dramatically increases carbohydrate requirements, fueling long runs, post-workout glycogen restoration and why an athlete's fitness remains more important than simply consuming more fuel.

Jordan also explains why blanket recommendations such as 60-90 g or 120 g of carbohydrate per hour may not be optimal for everyone. Individual carbohydrate oxidation rates, gut tolerance and training history can all influence how much carbohydrate an athlete can actually use. They finish with bone health, practical carbohydrate choices including white rice, bread, fruit and honey, and why developing good whole-food habits remains important for long-term health.

Timestamps

00:00 Meet Jordan Sullivan
00:05 Weight Loss During Training
00:40 Why Calories In Out Fails
04:28 RED-S Risk And Nuance
06:12 Diagnosing RED-S Limits
07:13 Intensity Versus Duration
08:04 Fight Camp Case Study
12:53 Performance Versus Health
14:17 Setting A Marathon Cut
16:20 Power To Weight Explained
20:24 Fueling And Periodization
24:46 Estimating Calorie Burn
27:06 Safe Weekly Loss Targets
33:32 Muscle Loss In A Deficit
38:15 Going Leaner 69 To 65
43:22 When To Cut In Marathon Block
44:11 Race Prep Weight Loss
45:25 Training Status Matters
53:11 Fueling Long Runs
54:31 Carbs Versus Fitness
01:02:56 Intensity Drives Carb Use
01:08:10 Personal Carb Oxidation
01:14:24 Bone Health Basics
01:16:39 Best Carb Food Choices
01:20:15 Whole Foods For Longevity
01:23:35 Wrap Up And Contacts

Matt recaps his 2:33 Sydney Marathon in jeans, then dives into recovery, weight loss, fueling, strength training, Melbourne Marathon goals and what comes next.

Matt Fox / Sweat Elite

Coaching: https://www.sweatelitecoaching.com/matt-fox/

Instagram: https://www.instagram.com/mattinglisfox/

Strava: https://www.strava.com/athletes/6248359

YouTube: https://www.youtube.com/@SweatElite

Sweat Elite: https://www.sweatelite.co/

Sweat Elite Instagram: https://www.instagram.com/sweatelite/

Three days after the Sydney Marathon, Matt breaks down his 2:33:38 run in jeans and what he is currently calling the fastest known marathon in jeans. He talks through the pacing strategy, running with the 2:35 pacer through 30km, dealing with hamstring cramping late in the race, how much the jeans may have slowed him down and how Sydney compares with a flatter marathon course.

Matt also goes deep into marathon recovery, including the roughly 310g of carbohydrates and 50g of protein he consumed in the first 90 minutes after finishing. He discusses sleep, returning to training after a marathon, strength and mobility work, cramping, chafing, shoe choices and why he believes his recovery has been significantly better than after many previous marathons.

Weight loss remains a major topic as Matt explains how he has gone from around 86kg to roughly 73kg over the past four months while continuing to train at a high level. He discusses calorie deficits on easier days, carbohydrate cycling around workouts and long runs, strength training while losing weight, GLP-1 use, maintaining power while getting lighter and why he believes reaching approximately 69kg could put him back around PB shape for Melbourne.

Matt finishes by answering listener questions on Sydney's hills, marathon course conversions, how long runners can continue improving with age, shoe durability, recovering between Sydney and Melbourne, preventing marathon cramps and future costume marathon attempts. He also shares his plan to move to Lisbon later this year and spend more time racing and training in Europe.

Episode Timestamps

00:00 Welcome back
01:02 Sydney Marathon Jeans Run
04:33 Pacing, Cramp and Gym
06:55 Recovery Carbs and Sleep
10:43 Guinness Record Confusion
14:18 Chafing and Gear Tips
15:15 Melbourne Goals and Weight Math
19:07 Comeback After Time Off
23:24 Strength Training While Cutting
26:49 Fat Loss Method and GLP-1
30:01 Calorie Tracking and Carb Loading
32:12 Carb Cycling and Weight Loss
33:45 Garmin Calorie Burn Debate
35:33 Healthy Leanness and Caveats
36:23 Weight Targets for Faster Marathons
37:48 Sydney Course Time Conversion
40:02 Crowds and PB Potential
40:44 Marathon PBs With Age
42:10 Running a Marathon in Jeans
43:18 Low-Calorie Days and GLP-1s
45:00 Shoe Rotation and Durability
46:02 Recovering for Melbourne Marathon
48:42 Costume Records and Charity
51:08 Collaborations, Cramps and Shoe Picks
54:09 Fueling Rules for Hard Days
56:21 Moving to Lisbon
58:51 More Diet Content and Wrap Up

Matt dives into the results of his recent super shoe testing at Griffith University, comparing 12 of the best Chinese racing shoes before putting the leading models up against some of the biggest Western brands. Using laboratory running economy testing at 17 km/h, the results produced some major surprises - including a sub-US$100 Chinese shoe outperforming several of the world's most established super shoes.

Matt Fox Links

Coaching: https://sweatelitecoaching.com/matt-fox/

Supporters Club: https://sweatelite.co/supporters-club/

Instagram: https://www.instagram.com/mattinglisfox/

Strava: https://www.strava.com/athletes/6248359

Email: matt@sweatelite.co

The Anta C202 G9 Edition 2 emerged as the best-performing Chinese shoe, ahead of the Li-Ning Feidian 6 Elite and Qiaodan Feiying Plaid 3.0. Matt breaks down the rankings, the impact price and expectations can have on perceived shoe performance, and just how much difference the right racing shoe could potentially make across a marathon.

Matt also looks ahead to the Sydney Marathon, where he plans to attempt the world record for the fastest marathon run in jeans. He discusses the Australian Championships uniform rules, the maths behind breaking the 2:34:45 record, Sydney's challenging course, and why the record may be considerably harder than he initially expected.

The episode finishes with Melbourne Marathon goals, the Fat Fox Method for managing body weight around marathon training, strength training, HYROX, longevity, an upcoming 5K attempt, and a preview of several upcoming podcast episodes.

Episode Chapters
00:00 Podcast cold open
00:35 Why test super shoes
02:52 Lab testing setup
04:14 Chinese shoe rankings
04:49 Dragonfly hype check
06:19 Price and placebo
08:22 Third place surprise
10:14 Western shoe clues
11:59 Anta wins overall
12:54 Name confusion explained
14:49 Who this applies to
16:40 How big the gains
19:04 Cost and who should test
21:33 My marathon shoe history
23:22 Next race Sydney plans
24:20 Jeans Champs rules
25:57 Record maths reality
27:55 Sydney trip logistics
30:12 Melbourne dreams and Kipchoge
31:09 Fat Fox Method
34:23 Getting leaner safely
36:22 Gym, HYROX and longevity
40:57 Early mornings and wrap-up
42:07 Jeans and 5K prediction
44:14 Next content teasers

Is getting lighter always the answer for runners chasing faster race times? Matt Fox is joined by Dr David Lipman for a short, sharp discussion about weight loss, performance, RED-S and the risks of taking leanness too far.

Dr David Lipman Links

Instagram: https://www.instagram.com/drdavidlipman/

Website: https://www.drdavidjlipman.com/

Listen to David's Podcast

For more conversations exploring the science, psychology and hidden stories behind sport, check out 1% Better - Hidden Stories in Sport, co-hosted by Xylon van Eyck and Dr David Lipman.

Matt Fox Links

Coaching: https://sweatelitecoaching.com/matt-fox/

Supporters Club: https://sweatelite.co/supporters-club/

Instagram: https://www.instagram.com/mattinglisfox/

Strava: https://www.strava.com/athletes/6248359

Email: matt@sweatelite.co

Matt and David explore why being lighter does not automatically make an athlete faster. Although reducing excess body fat may improve running economy and performance, there is a lower limit where continued weight loss can begin to compromise health, recovery and long-term performance.

Matt shares his own experience of becoming faster after losing weight, while David explains why the human body cannot be treated like a simple machine. Some body fat may provide an important energy buffer because the absorption and use of fuel can vary between athletes and from day to day.

They examine Ryan Hall's experience as a cautionary example. Hall initially improved while becoming extremely lean, but his performance and health eventually declined after taking the process too far. This temporary improvement can create a dangerous "more is better" mindset, where athletes continue restricting food because the early results appear positive.

The conversation also breaks down Relative Energy Deficiency in Sport, commonly known as RED-S. Rather than viewing RED-S as the result of one isolated mistake, David describes it using a stress bucket model. Training load, inadequate fueling, poor sleep, work pressure and other life stressors can accumulate until the athlete's ability to recover is overwhelmed.

Matt and David discuss carbohydrate periodization and carb cycling, including when lower-carbohydrate training may have a place within an endurance program. However, they stress that these strategies do not eliminate the risks of chronic under-fueling. Athletes still require adequate carbohydrates, protein and dietary fat to support performance, recovery and overall health.

They also cover behaviours associated with disordered eating, the spectrum between structured nutrition and unhealthy restriction, whether runners should deliberately lose muscle mass, and the difficult tradeoffs that can exist between short-term performance and long-term health.

Episode Timestamps

00:00 Is Lighter Always Faster?
00:43 Fat Buffer and Absorption
01:31 Ryan Hall Cautionary Tale
02:38 When Leanness Backfires
03:28 RED-S and the Stress Bucket
06:27 Carb Cycling and Risk
08:43 Macronutrients and Carb Periodization
10:29 The Disordered Eating Spectrum
12:13 Muscle Mass vs Running Goals
13:20 Health and Performance Tradeoffs
14:28 Wrap Up and Thanks

This conversation is provided for general educational purposes and is not individual medical or nutritional advice. Athletes concerned about RED-S, disordered eating or persistent under-fueling should speak with a qualified healthcare professional.

Welcome back to another unstructured In My Opinion episode. Matt shares an update on losing weight to run faster, the explosion of Chinese super shoes and Dynafish, a potential marathon world record attempt in jeans, HYROX plans, coaching updates and why he has backed away from frequent sauna use.

Be coached by Matt:
https://www.sweatelitecoaching.com/coaching-2026

Join the Shareholders Club / Private Podcast Feed:
https://www.sweatelite.co/shareholders

Matt Instagram:
https://www.instagram.com/mattinglisfox/

Matt Training Log - Strava:
https://www.strava.com/athletes/6248359/

Contact Matt:
matt@sweatelite.co

Matt opens with updates on the Sweat Elite Podcast, including changes to the private feed, a new weekly subscriber hangout and a small number of coaching opportunities becoming available.

The main discussion centres around losing weight to run faster, prompted partly by Josh Kerr's visible change in body composition alongside his recent performances. Matt reflects on his own marathon career, including a period where gaining roughly 3.5 kg coincided with slower marathon performances before intentionally losing around 4 kg and returning to consistent sub-2:20 racing.

Matt explains the simple approach he has personally used - maintaining a modest calorie deficit on most days while prioritising high-volume, satiating foods, then aggressively increasing carbohydrate intake around important training. Rather than trying to remain perfectly fuelled every hour of every day, he discusses using roughly 12-hour windows before major sessions and races to maximise carbohydrate availability, followed by substantial refuelling afterwards.

He also discusses why he avoids obsessing over daily scale weight, instead looking at longer-term trends and carbohydrate cycles. Matt believes intentional weight-loss phases should generally be relatively short - around 6 to 12 weeks for most athletes and rarely beyond 20 weeks - rather than becoming a permanent part of training.

The conversation also tackles the stigma surrounding weight loss in endurance sport, RED-S, disordered eating and the potential danger of becoming obsessed with numbers. Matt stresses that this approach is only relevant to runners who genuinely have weight they can healthily lose and that improving performance should never come at the expense of long-term health.

Later in the episode, Matt shares updates from the Chinese running shoe world, including upcoming laboratory testing of several Chinese super shoes and the rapid growth surrounding Dynafish. He discusses distribution delays, demand in China and plans for bringing more shoes into international markets.

Matt also considers racing the Sydney Marathon in jeans and potentially attempting the marathon world record for running in jeans, before discussing his future racing ambitions, interest in trying HYROX and whether an Ironman is something he would ever consider.

Finally, Matt explains why he has stopped frequent sauna sessions after noticing increasing fatigue and deteriorating training quality, despite initially introducing sauna as part of his marathon preparation.

Topics:

00:00 Welcome and Setup
00:27 Topics and Context
02:46 Pro Podcast Changes
03:46 Subscriber Hangouts
06:05 Coaching Spots Open
07:12 Why Weight Matters
08:18 Josh Kerr Example
09:45 My Marathon Weight Shift
14:41 Stigma and Pushback
20:08 Simple Weight Loss Framework
24:34 Carb Timing for Workouts
28:59 Risks and Obsession Trap
30:38 Carb Cycles Not Scales
31:44 Avoid Number Obsession
32:47 Who Should Cut Weight
35:46 Coaching And Stigma
37:36 Chinese Shoe Lab Tests
39:39 Dynafish Distribution Plans
43:36 Sydney Jeans Marathon
45:40 Weight Loss And Future Goals
50:55 HYROX Versus Ironman
52:31 Sauna Fatigue Lesson
57:25 Wrap Up And Next Steps

Race Weight and Carb Cycling: Losing Weight to Get Faster Without Sacrificing Key Workouts

Welcome back to another short, sharp sub 15-minute episode. Today, I discuss the relationship between race weight and endurance performance, using examples including Josh Kerr, the new mile world record holder, Comrades Marathon winner George Kusche, and Olympic triathlon champion Kristian Blummenfelt.

I explain how losing weight has helped me improve my own marathon time from 2:35 to 2:18, while also addressing the risks of aggressive dieting and underfueling. This episode is not intended for anyone with a history of eating disorders, and I am sharing my personal experience rather than professional nutritional advice.

I break down how I use a moderate calorie deficit on most days while carb cycling around important workouts. The goal is to fuel heavily with carbohydrates for approximately 12 hours before and three hours after key sessions, then return to lower-calorie, filling foods during easier periods.

Matt's Links

Coaching: https://sweatelitecoaching.com/matt-fox/

Supporters Club: https://sweatelite.co/supporters-club/

Email: matt@sweatelite.co

Instagram: https://www.instagram.com/mattinglisfox/

Strava: https://www.strava.com/athletes/6248359

Episode Timestamps

00:00 Elite Weight Clues
02:05 Podcast Setup and Warning
03:55 My Race Weight Journey
06:04 Critics and Risk
08:14 Calorie Deficit Basics
10:21 Carb Cycling for Workouts
12:52 Foods That Keep You Full
14:11 Resources and Wrap Up

Jack Kelly from The Triathlon Hour returns to the Sweat Elite Podcast for a fun challenge - ranking six running workouts from manageable to completely diabolical.

Along the way, we debate stop recoveries versus float recoveries, discuss whether marathon pace should be guided by effort or pace, explore the biggest differences between training for running and triathlon, and explain why some workouts are far harder mentally than physically. We also share how weather, fueling, terrain and fatigue should influence the execution of key marathon sessions.

The episode finishes with the hardest workouts either of us has ever designed. Jack unveils a brutal 29.6 km session combining marathon pace with repeated half-marathon-pace intervals, while Matt shares a relentless 25 km progressive run that finishes faster than goal marathon pace. If you're looking for new training ideas or simply want to hear two coaches dissect what makes a great workout, this episode is packed with practical insights and plenty of debate.

Jack Kelly / The Triathlon Hour

Instagram:
https://www.instagram.com/jackkellytri/

Podcast:
https://open.spotify.com/show/4gjZJMzMev7LvylirVjIGD?si=b3f1e6f64841417d

YouTube:
https://www.youtube.com/@thetriathlonhour

Matt Fox / Sweat Elite

Coaching:
https://www.sweatelitecoaching.com/matt-fox/

Instagram:
https://www.instagram.com/mattinglisfox/

Strava:
https://www.strava.com/athletes/6248359

YouTube:
https://www.youtube.com/@SweatElite

Timestamps

00:00 Welcome Back Banter
00:53 The Hat Story
02:48 Six Workout Challenge
06:02 Stop Rest Debate
07:57 Workout 1 - Most People Could Do
10:21 Workout 2 - Moderate
15:10 Workout 3 - Challenging
21:59 Workout 4 - Hard
29:36 Level 5 - Really really hard
36:56 Level 6 - Diabolicaly hard!
43:51 Fueling Weather Logistics
46:27 Wrap Up Next Rivalry Tease

These workouts are discussed for educational and entertainment purposes. Adjust the volume, intensity and recovery to suit your experience, current fitness and training goals.