WHAT ARE THE NUTRIENTS?

The foods we eat contain nutrients. Nutrients are substances required by the body to perform its basic functions. Nutrients must be obtained from our diet since the human body can not make them. Nutrients have one or more of three basic functions: they provide energy, contribute to body structure, and/or regulate chemical processes in the body. These basic functions allow us to detect and respond to environmental surroundings, move, excrete wastes, breathe, grow, and reproduce. There are six classes of nutrients required for the body to function and maintain overall health. These are carbohydrates, lipids, proteins, water, vitamins, and minerals. Foods also contain non-nutrient that may be harmful such as natural toxins common in plant foods and additives like some dyes and preservatives or beneficial like antioxidants.

KEY FUNCTIONS OF  THE 6 ESSENTIAL NUTRIENTS

Daily training diet requirements

The basic training diet should be sufficient to:

• provide enough energy and nutrients to meet the demands of training and exercise
• enhance adaptation and recovery between training sessions
• include a wide variety of foods like wholegrain breads and cereals, vegetables(particularly leafy green varieties), fruit, lean meat and low-fat dairy products to enhance long term nutrition habits and behaviours
• enable the athlete to achieve optimal body weight and body fat levels for performance
• provide adequate fluids to ensure maximum hydration before, during and after exercise
• promote the short and long-term health of athletes.

The athlete’s diet

An athlete’s diet should be similar to that recommended for the general public, with energy intake divided into:

• 45 to 65% from carbohydrates
• 15 to 25% from protein
• 20 to 35% from fat.

Athletes who exercise strenuously for more than 60 to 90 minutes every day may need to increase the amount of energy they consume, particularly from carbohydrate sources. 

Guidelines for carbohydrate and protein based on grams intake per kilogram (g/kg) of body weight are also available.

The current recommendations for fat intake are for most athletes to follow similar recommendations to those given for the general community, with the preference for fats coming from olive oils, avocado, nuts and seeds 

Athletes should also aim to minimise intake of high-fat foods such as biscuits, cakes, pastries, chips and fried foods.

Pre-event meal

The pre-event meal is an important part of the athlete’s pre-exercise preparation.

A high-carbohydrate meal 3 to 4 hours before exercise is thought to have a positive effect on performance. A small snack one to 2 hours before exercise may also benefit performance.

It is important to ensure good hydration prior to an event. Consuming approximately 500 ml of fluid in the 2 to 4 hours prior to an event may be a good general strategy to take. 

Some people may experience a negative response to eating close to exercise. A meal high in fat, protein or fiber  is likely to increase the risk of digestive discomfort. It is recommended that meals just before exercise should be high in  carbohydrates as they do not cause gastrointestinal upset.

Examples of appropriate pre-exercise meals and snacks include cereal and low-fat milk, toast/muffins/crumpets, fruit salad and yoghurt, pasta with tomato-based sauce, a low-fat breakfast or muesli bar, or low-fat creamed rice. Liquid meal supplements may also be appropriate, particularly for athletes who suffer from pre-event nerves.

For athletes involved in events lasting less than 60 minutes in duration, a mouth rinse with a carbohydrate beverage may be sufficient to help improve performance. Benefits of this strategy appear to relate to effects on the brain and central nervous system.

Eating during exercise

During exercise lasting more than 60 minutes, an intake of carbohydrate is required to top up blood glucose levels and delay fatigue.

Current recommendations suggest 30 to 60 g of carbohydrate is sufficient, and can be in the form of lollies, sports gels, sports drinks, low-fat muesli and sports bars or sandwiches with white bread.

It is important to start your intake early in exercise and to consume regular amounts throughout the exercise period.

It is also important to consume regular fluid during prolonged exercise to avoid dehydration. Sports drinks, diluted fruit juice and water are suitable choices. For people exercising for more than 4 hours, up to 90 grams of carbohydrate per hour is recommended.

Protein and sporting performance

Protein is an important part of a training diet and plays a key role in post-exercise recovery and repair. Protein needs are generally met (and often exceeded) by most athletes who consume sufficient energy in their diet.

The amount of protein recommended for sporting people is only slightly higher than that recommended for the general public. For example:

• General public and active people – the daily recommended amount of protein is 0.8 to 1.0 g/kg of body weight (a 60 kg person should eat around 45 to 60 g of protein daily).
• Sports people involved in non-endurance events – people who exercise daily for 45 to 60 minutes should consume between 1.0 to 1.2 g/kg of body weight per day.
• Sports people involved in endurance events and strength events – people who exercise for longer periods (more than one hour) or who are involved in strength exercise, such as weight lifting, should consume between 1.2 to 2.0 g protein/kg of body weight per day.
• Athletes trying to lose weight on a reduced energy diet – increased protein intakes up to 2.0 g/kg of body weight per day can be beneficial in reducing loss of muscle mass.

For athletes interested in increasing lean mass or muscle protein synthesis, consumption of a high-quality protein source such as whey protein or milk containing around 20 to 25 g protein in close proximity to exercise (for example, within the period immediately to 2 hours after exercise) may be beneficial.

As a general approach to achieving optimal protein intakes, it is suggested to space out protein intake fairly evenly over the course of a day, for instance around 25 to 30 g protein every 3 to 5 hours, including as part of regular meals.

There is currently a lack of evidence to show that protein supplements directly improve athletic performance. Therefore, for most athletes, additional protein supplements are unlikely to improve sport performance.

Water and sporting performance

Dehydration can impair athletic performance and, in extreme cases, may lead to collapse and even death.

Drinking plenty of fluids before, during and after exercise is very important. Don’t wait until you are thirsty. Fluid intake is particularly important for events lasting more than 60 minutes, of high intensity or in warm conditions. 

Water is a suitable drink, but sports drinks may be required, especially in endurance events or warm climates. Sports drinks contain some sodium, which helps absorption. A sodium content of 30 mmol/L (millimoles per litre) appears suitable in sports nutrition.

While insufficient hydration is a problem for many athletes, excess hydration may also be potentially dangerous. In rare cases, athletes might consume excessive amounts of fluids that dilute the blood too much, causing a low blood concentration of sodium. This condition is called hyponatraemia, which can potentially lead to seizures, collapse, coma or even death if not treated appropriately.

Consuming fluids at a level of 400 to 800 ml per hour of exercise might be a suitable starting point to avoid dehydration and hyponatraemia, although intake should ideally be customised to individual athletes, considering variable factors such as climate, sweat rates and tolerance.

Even in the military, where maintaining physical fitness remains a job requirement and a key component of military readiness, thousands of service members struggle with being overweight.

Physical fitness is more than just a set of scores measuring your body-mass index, run times, or how many push-ups you can do. Optimizing your physical fitness requires a good diet, healthy lifestyle, strength, flexibility, balance, and endurance all working together.

Yet keeping a healthy body weight is correlated with all those components and is essential for long term health, fitness and personal readiness.

Injury Risk

About 17% of soldiers are considered obese, and this impacts readiness because being overweight increases the risk of musculoskeletal injuries by putting extra strain on the body, according to Army 1st Lt. Cara Adams, a registered dietitian and the chief of outpatient nutrition at General Leonard Wood Army Community Hospital

Leonard Wood TRICARE

in Missouri.

Noncombat musculoskeletal injuries account for nearly 60% of soldiers’ limited duty days and are cited in 65% of cases where soldiers cannot deploy for medical reasons, according to a recent study

Academic.oup.com

. These injuries affect readiness through increased limited duty days, decreased deployability rates, and increased medical separation rates.

Eating Better

Consuming a balanced diet rich in nutrients can “help prevent stress fractures and other anomalies that prevent military personnel from being ready for duty,” Adams said.

Good nutrition goes beyond just calories and protein, she pointed out. “Our bodies were created to absorb and use nutrients from whole foods.”

She suggested service members “start with the basics” by simply taking an honest look at what they eat and drink every single day. “Are you setting your body and your health up for success by consuming a variety of whole foods?” she asked.

Whole foods are foods that are not heavily processed or refined, like fruits, vegetables, nuts and seeds, beans and legumes, whole grains, meat, fish, and eggs. “The more of these types of foods that end up in your diet, and the more variety in your diet – the better,” Adams said.

“Unfortunately, our current food environment seems at odds with healthy eating,” she said. “The evolutionary discrepancy between our brain’s desire for calorie-dense foods to ensure survival and the ultra-processed food, sedentary living, and stressful lifestyle of today’s culture creates the perfect storm for constant cravings, weight gain, and poor health.”

Moreover, many fitness-oriented service members are focused more on cure-all dietary supplements rather than their core diet.

“Many soldiers are too concerned with which pre-workout supplement they should be taking or how much creatine they should be having when their diet primarily consists of fast food and empty calories. Prioritize food,” Adams said.

A good rule is to avoid any “diet” that is not truly stainable, Adams advised.

“Many soldiers want quick fixes to weight loss. They want to go vegan or vegetarian simply to lose weight, yet chicken and fish are their favorite foods. I remind patients that they do not have to completely eliminate any of their favorite foods to achieve their health goals. In fact, I encourage them not to.”

The most important goal is a healthy diet and regular physical activity. “Food is the fuel that energizes, strengthens, and helps the body recover from physical activity. A healthy diet and physical activity can help individuals not only achieve, but better maintain a healthy weight.”

“It can help reduce the risk of heart disease, stroke, and certain cancers, as well as strengthen bone, muscles, and joints,” Adams said.

Regular exercise and proper nutrition “have been shown to improve levels of happiness, increase energy levels, and increase your chances of living longer. It can also improve sleeping habits and sleep quality and help you build a stronger immune system,” she said.

Changing Bad Habits

Leah Roberts said she tries to “reframe” her patients’ triggers for bad nutrition that can contribute to weight gain. Roberts is a licensed dietitian and certified diabetes care and education specialist at the Army’s Kimbrough Ambulatory Care Center

Kimbrough Ambulatory Care Center

at Fort Meade, Maryland.

Her primary recommendation is that overweight service members should cook their meals at home or eat at their installation’s dining facility where there are freshly cooked hot meals and other healthy foods available three times a day.

Avoid meal delivery services, Roberts suggested. During the COVID-19 pandemic “we’ve created a new culture of fast food and delivery service” that leads to unhealthy eating, she said.

Too much work and after-work or after-school activities frequently lead to settling for comfort foods or convenience foods because there just doesn’t seem to be time to shop for healthy foods, Roberts said.

Her second recommendation is to “avoid sodas, juices and sweet tea.” They are full of sugar and empty calories.

Tip number three on Roberts” list: “Have a plan.”

“People struggle the most about how to have food that is nutritious, easy to have on hand, and easy to prepare during busy weeknight schedules,” she said.

Her most important component, she said, is to encourage small goals that are modifiable but consistent.

For instance, she makes her patients’ first goal to lose 5% of their body weight. “I deal with people who weigh 220 or 230 pounds. When they calculate how many pounds to lose to get to that first goal, they say, ‘I can do this.'”

British 24 Hour Ration Packs

The British use a ration called the 24-Hour Operational Ration Pack. Previous versions of this ration were called the ration packs (GS for General Service). Those rations included a lot of food in cans. By 1999, the GS rations were phased out and the newer GP (General Purpose) ration packs became the primary operational ration pack.

Features of the 24-Hour operational ration pack are:

• An individual ration for normal use in the field.
• Ration is designed to feed one person for one day.
• It has been designed to provide a balanced nutritional diet.
• Can be eaten hot or cold.
• ORP provides an average of 3800-4200 Kcal per ration.
• Ration is 10% protein, no more than 35% fat, 55% carbohydrate.
• Continuous consumption up to 15 days, ideally no longer than 30 days due to nutritional qualities.
• 7 Menus consisting of Breakfast, Snack, Main Meal, Beverages, Sundries (matches, tissues etc)
• Hot meals in flexible foil pouches.
• Rations packed in waterproof outer cardboard boxes.
• All ORPs have a shelf life of at least 3 years.
• Presently, up to 2.5 million rations produced annually.
• British military ORPs are packed in a production line within HM (Her Majesty?s) Naval base at Portsmouth, England, UK.

The breakfast, main meal and dessert rations are of the boil-in-a-bag (retort pouch) variety and can be heated up by submerging them in boiling water heated up on a Hexamine Stove (see below). The soup and drinks are in instant and/or powdered form.

One useful feature of the GP rations is on the box itself. As you can see from this picture, each box has a target and range card printed on the side.

British soldiers are issued Hexamine stoves, also called Tommy Cookers. These pocket-sized, foldable, solid fuel metal stoves use blocks of hexamine for fuel. These stoves be can used to heat up water for coffee/tea and to warm up the entrees. They also come with an adapter to hold a metal mug/canteen cup. These stoves are similar in design to the European Esbit stoves but are larger and come with different fuel. They come issued in a brown paper wrapper with 8 fuel tablets in a waxed box. The standard issue is one cooker every three days but with fuel refill every day. The fuel with these is very toxic, smells dreadful and very difficult to light as it is very waxy. Despite all this the smell of it on a cold morning is beautiful!