How to Eat to Optimize Training for Open Water Swimmers

How to Eat to Optimize Training for Open Water Swimmers

Guest post by Dawn Weatherwax, RD, CSSD, LD, ATC, CSCS

Quantity, Quality, Body Composition & Planning

Open Water Swimmers put in countless hours of training week in and week out to reach their goals. But most don’t put the same time or attention into the nutrition regimen to support that training. With over 25 years of experience working with athletes, I’ve identified four areas of nutrition swimmers should focus on to optimize their training.


Calories are the fuel needed for ideal performance as well as optimal recovery.  A common problem I see is athletes don’t know how many calories they regularly consume or how to ratchet the quantity up or down based on their training load.

Hunger and fullness cues just simply aren’t a good barometer.  By not consuming enough calories, a surprising number of athletes will regularly force their body into survival mode.  Especially with high training loads it is easy to under fuel the muscles where the body will hold on to fat and lose muscle. This will lead to sub-optimal training sessions and risk general fatigue and illness.

Below is a simple benchmark to make sure you’re getting the calories you need to fuel your training.

If you’re training a total of 5-8 hours a week in the water or dry land:

  • A female athlete will require at least 2000-2800 calories a day
  • A male athlete will require from 2300-3000 calories a day
  • If you’re training a total of 15-20 hours a week in the water or dry land:
  • A female athlete will require at least 2300-3800 calories a day.
  • A male athlete will require at least 2500-4500 calories a day.

These are just estimates and there are many factors that could alter these recommendations, but if you are consuming less than these amounts I would recommend seeking out assistance to ensure not chronically under eating and losing muscle.  


What an athlete eats is equally important to the quantity. Each athlete has different needs and goals, and truly optimize training goals, I always recommend  working with a Sports Dietitian to help customize meal plans to match the athlete’s body and training plan. That being said below is a list of general guidelines to keep track of.

  1. Try to keep added sugars below 30g a day, except for those consumed, immediately prior, during or immediately after training
  2. Aim for 30-40g  of fiber a day
  3. Aim for 1g of protein per pound of lean weight (lean weight is everything but fat on the body)
  4. Keep Saturated fats to 10% or less of total caloric intake
  5. Aim for 100% of your daily dose of Vitamins C, A & E through food
  6. Hydrate at least ½ your body weight in fluid ounces a day in addition to that consumed during training

If you’re training a total of 5-8 hours a week in the water or dry land a few supplements to consider are: 

  • Calcium
  • Magnesium
  • Omega 3’s (fish oil/DHA & EPA)
  • Vitamin D3
  • Vitamin B12
  • Iron
  • Zinc
  • Leucine (protein that builds muscle)
  • Sodium

If you’re training a total of 15-20 hours a week in the water or dry land, a few supplements to consider are:

  • Supplements to consider:
  • Collagen and Resync Recovery (Nitric Oxide) for soreness and reducing inflammation
  • BCAA’s (Branch Chain Amino Acids) prior to training for mental fatigue and muscle recovery
  • Tart Cherry Concentrate after training or before bed for muscle soreness/helping with sleep
  • Electrolytes: Sodium, Potassium, Calcium, Magnesium

These are just suggestions and are not intended to replace any medical needs or interventions.

One additional recommendation is to track the quantity and quality of food being consumed is to The Cronometer App. It is free and a good place to start.

If you’re looking for a more scientific approach, seek out a medical expert who can measure the calories the athlete is burning at rest. At my office we use a FDA metabolic device called the MedGem.

Body Composition

Do you know your body composition?  Body comp is very simply how many pounds lean and how many pounds fat you are. So many athletes do not have a scientific approach to their nutritional or training needs rooted in this fundamental metric.

When an athlete knows their body composition, it becomes easier to set goals.  Solely relying on weight is not only insufficient, it can be dangerous, since weight provides zero indication of what is going on inside the body.

Many endurance athletes for example lack muscle since prolonged cardio in their training provides little in the way of resistance training. 

At my office we use the BodPod to determine body composition.   If you are serious about your sport, I highly recommend getting your body composition tested and set nutrition and training goals based on it.

Athlete Guidelines for Body Composition

Female Athletes: 17-30% body fat & ~95-100lb of lean weight at 5’4”

(add 3-5 lb lean weight per additional inch height)

Males 7-20% body fat and at least 125-130lb of lean weight at 5’8”

(add 4-6lb of lean weight per additional inch height)

These are guidelines and not absolutes.  Each athlete is different and some will have much more lean weight than the numbers above and perform optimally.  The goal is not to lose lean weight, and in fact, many need to gain more lean weight to improve performance.

I highly recommend measuring body composition and working with someone who understands your specific goals.


While many athletes can be religious in their training plans for the week, month or season,  it is common for these same athletes to have little to no plan around their nutrition. I always recommend writing down what you plan to eat and drink for at least a week at a time. Some research shows this simple step of writing it down will make you 80% more likely to follow the plan.

It is important to make sure you are adding the calories and necessary supplements as activity increases to optimize training, recovery and general health.  

As an athlete if you want to maximize your training and performance outcomes, remove the guess work, save time and minimize sickness, it is important to make nutrition as much a part of your regimen as the training.

By Dawn Weatherwax, RD, CSSD, LD, ATC, CSCS

Dawn Weatherwax
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