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Triathlon nutrition – our ultimate guide to fuelling

Your fuelling strategy for triathlon should be a shifting picture, reflecting your training and the time of year. Here we unlock the secrets of periodised nutrition to make you a stronger, faster triathlete…

(Image: Remy Whiting)

You spend thousands of laps refining your swim technique, hours poring over cutting-edge carbon components and wear out dozens of run shoes. But do you apply the same dedication to your nutrition plan?

Many of us fall into the trap of eating what we want without stopping to think ‘Hang on, is my nutrition plan suited to my training at this particular time of the year?’.

What is periodised nutrition?

Enter periodised nutrition. In essence, this fuelling template matches your training macrocycle and the intensity of your training, but in the case of nutrition, this is broken down into the following phases: Base, Build, Competition and Transition.

We’ve timed the phases here to begin in early-mid January, peaking for the triathlon race season in early June (although this is adaptable if your season starts a little earlier or later).

A rough guide will see the Base Phase lasting around three months from January until April, the Build Phase lasting two months until June and the Competition Phase totalling the six opening weeks of your race season.

The Transition Phase encompasses the final weeks of the race season and lasts until the end of the year, when the Base Phase is set to begin again.

While each phase varies, there are some nutrition principles that apply all year round, according to coach Bob Seebohar, author of the book Nutrition Periodisation for Athletes on the subject.

“Choose foods rich in beta-carotene, vitamin C, vitamin E and zinc to improve immune function,” says Seebohar. “Also, choose polyunsaturated and monosaturated fats over saturated fats, and keep a written three-to-five-day food diary when you feel that your eating habits are lacking, to begin remedying the situation.”

Also remember this is real life, so aim for the 80:20 rule – that is, 80% of what you eat should be healthy, with 20% left to your own discretion. Right, onto that 80%…

What should I eat in the base phase?

The chimes of Big Ben still echo in your ears – as does the sound of masticating mince pies, glugging Glenfiddich and listening to Graham Norton. Yes, Christmas may well bring the family together, but it’s distinctly divisive when it comes to reaching your triathlon goals, with studies showing the average weight increase is 5lb.

“That’s why body composition is so important to the base period,” says sports nutritionist Drew Price. “You’re looking to lower your weight and now’s the perfect time to do it because training intensity should be low.”

Beyond cutting the pounds, improving your aerobic capacity is key, achieved via long sessions at an intensity that will focus on utilising oxygen to create energy.

Nutritionally this means you can reduce high-intensity fuelling carbs and increase the proportion of energy derived from protein and good fats.

“Depending on the amount of training you do, your carbohydrate intake should be 6-9g per kilogramme of bodyweight,” says Price. “Six is for athletes on less training with a higher body fat percentage. Protein nestles between 1.2g and 1.6g per kg, with fat around 0.9g-1g per kg.”

You might think cutting carbs and increasing fats is counter-intuitive to losing weight, but an excess of carbs is absorbed into the body as fat.

Good fats, like olive oil, avocado, nuts and seeds, are also more satiating than carbs, meaning you’ll feel fuller for longer.

Take a caffeine hit

Lower glycogen levels and lower intensity also guide your body to becoming a more proficient fat-burning machine, heightened by integrating fasted sessions, where you enter the workout in a glycogen-depleted state.

We delved into this deeper in issue 306’s Performance pages, but once a week is fine for many, ideally before breakfast following the night’s fast. However, for those of you regularly shadowing the age-group podia, you could experiment with more fasted sessions during the base phase.

“I tend to do a couple of runs each week and a longish ride (2.5-4hrs) in a fasted state,” says Michelin chef and world age-group duathlon champion Alan Murchison. “However, this is for experienced athletes only as there’s a real chance of bonking or running out of fuel.”

And if you’re concerned that your glycogen-deprived work output is simply too low for your ego to handle, there are tweaks that can help.

“When athletes train with low glycogen levels, their power output is reduced by 7-8%,” says professor of exercise metabolism, John Hawley. “However, we’ve shown that you can reduce that deficit by consuming caffeine, cutting power loss to around 3.5%.”

The preparation phase should also see an increase in antioxidants to boost immunity.

According to the NHS, you’re 80% more likely to pick up a cold in the winter, so cut down on pasta and rice, and take on more carbs from colourful vegetables. They’re a great source of vitamins and minerals, as are liver and kidney.

Base breakdown

The base period is the time to try out different wholefoods,” says Price. This period is characterised by a reduced carbohydrate intake, that space in your macronutrient cupboard now occupied by higher levels of protein, fat and fibre.

Also up the antioxidant levels to fend off common winter ailments and keep snacks to a minimum, though when you do graze, ensure it’s healthy foods like almonds that replace the urge for Pringles.

The daily breakfast of Helvellyn 2014 victor Alex Lawton isn’t a bad one to follow. “During the base period, my favourite is porridge with water (I have milk when increasing calorie requirements), including oats, pumpkin seeds, sultanas, cherries, blackcurrants and grapes.”

What should I eat in the build phase?

You’ve laid your aerobic foundations and refined technique. Now, it’s time to add speed and that comes from raising the intensity of your sessions. To fuel that extra effort, you need to tap into more instant fuel reserves – which means an increase in carbs.

“During the build phase, carb intake should rise to 8-12g per kg,” says sports nutritionist Drew Price. “Protein intake also increases to around 1.5g-2g per kg. Fat remains around the 1g per kg mark.”

Warning: for those who haven’t reached their goal triathlon weight, don’t fall into the trap of keeping carbs down as per the base phase. As chef and athlete Alan Murchison says, increasing intensity on a diet based on few carbs “leads to lethargy, feeling heavy and potential illness”.

That increase in carbohydrates derives from three key areas: general meals (including more pasta and rice), an increase in healthy snacking (to keep your glycogen levels topped up to maximise training efficiency, especially as many of you will be training twice a day) and a focus on sports foods (helping you to maintain high levels through the session).

You should also look at different protein drinks for recovery…

“We used to think protein was just for muscle-heads, but it’s not,” says professor John Hawley. “I had a bodybuilding workmate down the corridor who used to stink of tuna. He’d be feeding protein throughout the day.

“But we did a study last year and these guys are right: it’s far better to take your protein in small 20g doses. However, it’s also beneficial to front-load protein early in the day, as it’ll help repair muscle damage from the day’s hard training.”

Protein increase

You should also think about increasing protein intake after running, because of the greater impact causing delayed onset muscle soreness (DOMS). This is especially true of downhill running, which accentuates the eccentric contraction of your gait.

With seasonal temperatures rising along with training intensity, hydration also becomes a greater issue.

What you drink before, during and after your session influences the effectiveness of your efforts, with the traditional model of weighing yourself pre- and post-session still one of the more reliable methods of gauging how much you should consume.

Just note that energy drinks aren’t needed for sessions of less than 60 minutes.

Finally, don’t ignore sodium requirements. “Think about salt tablets,” says coach Bob Seebohar. “Depending on the race environment and distance – definitely for long-course triathlon – these could be of benefit. Try them during long bricks to see how you cope.”

Build advice

Now’s the time to increase quality complex carbohydrates and protein. Experiment and find the ones that are easy to consume in high volume, and not too difficult to digest, and ensure that you’re matching your increased calorie expenditure.

“During this phase, my calorie count probably increases by 300-500 through the addition of extra snacks between sessions,” says athlete Alex Lawton.

“Typically this would be either a banana with peanut butter, wholegrain brown rice cakes (again with some peanut butter and maybe two bananas if really hungry) or a small mug of muesli with milk.”

You also need to remain hydrated, which can be achieved by not only drinks but foods too.

What should I eat in the competition phase?

Calorie requirements are difficult to prescribe in the competition phase, with much of that percentage over to you and how you felt during the build phase.

“If you’re racing for less than five hours, you can probably follow the nutrition guidelines in the pre-race cycle (namely the build period),” says coach Seebohar.

“However, if you’re racing over that period, especially over 12 hours, you can increase carb intake from 7g per kg up to 19g per kg, protein between 1.2g and 2g per kg and fat from 0.8-3g per kg.”

This competition phase includes the taper – the period where you lower volume but maintain intensity.

You’d think that extra rest would be a physical and mental godsend, but we all know that the thought of not training hard confuses your mind. ‘This’ll lose fitness,’ your cerebellum says. It won’t. Be strong…

Once your taper arrives, it’s time to carbo-load, unless you’re a particularly swift sprint-distance athlete. “Carbo-loading – essentially increasing the amount of carbs you ingest – is useful for athletes racing for 90 minutes or more,” says professor Hawley, though he adds that you must remain pragmatic during this period.

“You will put on weight because when you store carbohydrate, you store water with it. But the benefits outweigh carrying that extra weight early in the race.”

Strip it back

Around two to three weeks out from a major race, it’s time to strip your diet right back, eating simple and clean foods. Chef and athlete Murchison advises eating similar dishes over and over again in that final two-week period.

“It’s dull, but you haven’t busted your balls for six months to ruin it by eating out lots and experimenting in the kitchen.”

That means no curry club… in other words, it’s time to join a culinary monastery. So, in with foods like pasta, light tomato-based sauces and cous cous. Low-fat protein like chicken and fish with every meal also keeps muscle repair on the menu.

“I also cover my back by heavily increasing my vitamin C intake to 3-4,000mg a day,” adds Murchison. “Travelling and meeting lots of new people pre-race exposes you to all sorts of germs, so this is a pretty good way to stay healthy.”

Just make sure you test this out beforehand to see how your stomach copes.

Fibre should also drop during the competition phase. With some of you racing up to 17 hours, the chances of unprompted evacuation increases with stool-loosening fibrous foods.

“Most of us are sensitive to residual fibre like you find on things like the outside of peppers or sweetcorn,” says sports nutritionist Price. “However, soluble fibre found in fruit like apples should be fine.”

It’s also good practice to mimic your eating patterns as per race build-up. And yes, that means if you start a race at 8am, it’s worth rising at 5.30am to consume your race-day breakfast.

As for race feeding, follow the sports food routine you’ve honed in training. The general rule is around 60g carbs per hour via drinks, bars and/or gels.

This is the most important phase of all. Get it wrong and you’ll feel lethargic and underperform. Get it right and you’ll reach your optimum. During the carbo-loading phase, grazing on good-quality high-carb snacks keeps the calorie count high.

If you’re a heavy sweater and are racing in the heat, or are racing over eight hours, it’s also wise to increase the amount of sodium you take in around three days before your race. “Just be sure to have ample water to wash it down,” says coach Seebohar.

Make sure you use the energy products that worked so well for you during the previous training cycle and ensure your hydration levels are high by monitoring urine colour. Pale yellow is the goal.

What should I eat in the transition phase?

You cross the line, pleased as punch (non-alcoholic, obviously) that you’ve smashed your PB. But don’t let that jubilation eclipse your recovery strategy.

“Once finished, your primary objectives are to ingest carbohydrates, protein and fluids,” says sports nutritionist Price. “You have plenty of fat in your body, so that’s not particularly needed.”

The ratio of carbohydrates to protein is open to debate, but a ratio of 2-4 carbs to 1 of protein is the accepted norm. Those carbs not only begin refilling glycogen levels, but also help to transport protein into the muscles to begin the repair process. A good-quality recovery drink, or chocolate milkshake, hits these percentages.

“Follow this within 45 minutes with a good solid meal containing plenty of carbohydrates and protein, like chicken or fish and pasta,” continues Price. “Include plenty of fibrous vegetables, too.”

Rehydrating’s also key immediately after the race. At events like Ironman, it’s impossible to retain optimum fluid levels throughout, so the golden rule post-race is that if you’ve lost 2kg, you’ll need 1.1 litres per kg to return to normal levels.

Essentially, that’s when your wee’s gone from rusty brown to pale yellow.

Back to base

The nutritional path you walk next depends on whether it’s your season end or one of many races.

Broadly speaking, if you have another race in a month or two, return to the nutritional template of the build phase; if you’ve hung your wetsuit out to dry, return to the base phase.

“If you’re racing again, the main question is: can you repeatedly carbo-load? I’d say yes,” says professor Hawley. “But not every two weeks, of course, or you’ll underperform.”

If you’re returning to the base phase, just remember that you’ve come off a nutritional strategy where you’ve been feeding every 2-3 hours. If you were to continue this grazing regime when your calorie output has dropped, you’ll soon pile on the pounds.

“This is easily prevented though,” says coach Seebohar. “Simply drop portion sizes and the number of times you eat each day.”

In macronutrient terms, this means carb intake dropping to 5-6g per kg, again focusing on greater amounts of fruit and veg replacing carbs like pasta and rice.

Protein hits the 1.2g per kg mark, though derived from lean meats rather than any protein supplements you might have taken during the build phase. Fat is around 0.8g-1g per kg.

Sports products should return to the cupboard, and alcohol intake, while inevitably rising to celebrate the race season, should remain moderate.

You should also reflect on what worked and what didn’t nutritionally, like you would with training. “It’s also the time to blow out with pizza and ice cream,” cheers athlete Lawton. “We’re not monks, after all!”

Transition tips

For most athletes, the transition phase will see them through to the off-season. If still racing throughout winter (e.g. duathlons), head back to the build phase.

That means reintroducing the wholefoods that you reduced during the competition period because of their high fibre content. Return your energy products to the larder and cut the amount of carbohydrate snacks from your feeding routine.

Finally, don’t overeat. Training is down; calorie requirements should reflect this. Just remember that it takes the brain around 20 minutes to realise that your stomach is full. Over to Seebohar:

“Eat slowly, enjoy your food, don’t eat in front of the TV and stop well before you think you’re full.”

Want more expert nutrition advice to help you smash every race? Then take a look at our nutrition section.

Top image: Remy Whiting

Profile image of James Witts James Witts Freelance sports writer and author


Former 220 Triathlon magazine editor James is a cycling and sports writer and editor who's been riding bikes impressively slowly since his first iridescent-blue Peugeot road bike back in the 80s. He's a regular contributor to a number of cycling and endurance-sports publications, plus he's authored four books: The Science of the Tour de France: Training secrets of the world’s best cyclists, Bike Book: Complete Bicycle Maintenance, Training Secrets of the World's Greatest Footballers: How Science is Transforming the Modern Game, and Riding With The Rocketmen: One Man's Journey on the Shoulders of Cycling Giants