By Matt O'Neill, MSc(Nut&Diet), APD
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Do you need to avoid soft drink to lose weight? Is fruit juice healthy? What's the best drink to have after a workout? In this article, I share the latest scientific thinking and practical advice for making the most of drinks in your diet.
If I asked you how many glasses of water you should drink each day, I'd bet you'd say at least 8 x 8 ounce (240 ml) glasses, which equals about 2 litres of water per day. This is common knowledge, but is it correct?
Whilst it may be a good idea, the “8 glasses a day” mantra lacks scientfic evidence, according to a comprehensive research review by Professor Heinz Valtin of the Dartmouth Medical School in the United States.  He says you can drink less water and still be healthy.
It appears that total fluid intake is important and you can get your fluid from more than just water. This makes sense, when you consider for example, that most fruits are are more than 80% water. Let's take a look at three more common questions about drinks in your diet.
Should I have a sports drink after a workout?
The standard sports drink is designed with the multi-purpose of replenishing your body with fluids and electrolytes lost in perspiration and carbohydrate used to fuel your workout. A 600 ml bottle of an 8% carbohydrate sports drink will provide around 50g of carbohydrate in the form of sugar.
Sports dietitians generally recommend sports drinks when you exercise for more than 60-90 minutes at a moderate or higher intensity. At this level your body can use around 50 g of carbohydrate per hour.
If you exercise a lot and endurance performance is paramount for you, then a sports drink is your best post-workout drink. If however, you exercise less or are working out with fat loss as your number one goal, then water will be adequate and won't load you up with 50 g of sugar (200 calories) that you don't need.
Sport water or `light' sports drinks have about half the sugar content as regular sports drinks. These are targeted more towards the calorie-conscious fitness buff who wants some flavour in their water rather than serious athletes who need the carbohydrates.
When should I take a protein shake?
Protein shakes can supplement your regular protein intake from foods to meet your daily requirements. Increasing evidence also shows protein shakes can have a role in optimising the timing and format your protein consumption for superior muscle recovery and growth.
Before you start taking a protein shake, assess your daily protein intake to see if you need to supplement this. Active adults should start with a target of 1.0g of protein per kilogram of body weight per day. If you are very active or are an athlete, aim to get between 1.2 - 1.8 g/kg/day, with the higher target for strength athletes.
Many people already meet these targets so there is no need to add more protein with supplements. If your prime goal is fat loss, watch you don't load up on protein shakes. When taken as extra snacks, protein shakes provide liquid calories that still need to be burnt up to see fat loss results.
If size and strength are your targets, then timing of protein intake is more important. Consuming 10-20g of protein within 30 minutes of a strenuous resistance workout can enhance muscle recovery by delivering a ready supply of amino acids exactly at the time your muscles need the protein building blocks.
To enhance the absorption rate of post-workout protein, you should consume it with an equal, if not greater amount of rapidly digested carbohydrate. This is where sugar is useful; because it helps protein get in faster. This means that a 100% protein shake, with few carbs is unlikely to optimise recovery. It's the mix of protein and carbs that does the job.
Is fruit juice healthy?
Most food guides list a 240 ml glass of fruit juice as an equivalent exchange to 1 medium piece of fruit. Even so, fruit juice concentrates the natural fructose fruit sugar, leaving behind most, if not all the fibre and some other nutrients.
Recognising this difference, a team of US experts published a Beverage Guidance System in the March 2006 issue of the American Journal of Clinical Nutrition (see below). It clearly lays out where different drinks fit into a healthy diet and the amounts recommended.
Fruits juice is classified as a Level 5 Beverage which is a “caloric beverage with some nutritional benefits”. Recommended daily fruit juice consumption is between 0-1 glasses per day. Practical application of this guideline would be having a glass of fruit juice at breakfast to take your daily multi-vitamin and fish oil capsules. Drinking more juice adds too many calories without a good dose of nutrients.
The exception is when you are very active and easily burn up the calories in fruit juice. In this case juice can be one of your easily consumed energy sources to fuel your workouts.
In conclusion, be drink-wise and share the low-down on liquids with your friends and clients.
In 2006, the US-based Beverage Guidance Council, headed by Professor Barry Popkin from the University of North Carolina drafted up a set of guidelines to help consumers choose what to drink. It's a good system that really helps put your beverage consumption habits in perspective. Note that 1 serving = 8 ounces (250 ml). Learn more at www.BeverageGuidancePanel.org
Level 1: Water
At least 20-50 ounces (600-1500 ml) with additional water if you limit other beverages.
Calories per serving = 0
Level 2: Unsweetened Coffee and Unsweetened Teas
Recommended Daily Tea Consumption: 0-5 servings (0-40 ounces / 0-1250 ml)
Recommended Daily Coffee Consumption: 0-4 servings (0-32 ounces / 0-960 ml)
Calories per Serving = 0
Level 3: Low-Fat (1%) or Skim (fat-free) Milk and Unsweetened/Fortified Soymilk
Recommended Daily Consumption: 0-2 servings (0-16 ounces / 480 ml)
Calories per Serving = 85-100
Level 4: Non-Caloric, Artificially-Sweetened Beverages
Recommended Daily Consumption: 0-4 servings (0-32 ounces / 0-960 ml)
Calories per Serving: 0
Level 5: Caloric Beverages with Some Nutritional Benefits
100% Fruit & Vegetable Juices and Smoothies
Recommended Daily Fruit Juice Consumption: 0-1 serving (0-8 ounces / 0-240 ml)
Calories Provided per Serving: 100-150
Recommended Daily Vegetable Juice Consumption: 0-1 serving daily (0-8 ounces / 0-240 ml)
Calories Provided per Serving: 50-100
Recommended General Consumption: Drink very sparingly.
Recommended Consumption for Endurance Athletic Events (strenuous activity that lasts over 90 minutes): 0-2 servings (0-16 ounces / 0-500 ml)
Calories per Serving: 0-40
Whole Milk and 2% Milk
Recommended Daily Consumption: 0 servings
Calories Provided per Serving: 120-160
Sweetened or Flavoured Low-Fat Milk
Recommended Consumption: Drink very sparingly.
Calories Provided per Serving: 150-160
Recommended Daily Consumption for Adult Women who Choose to Drink Alcohol: 0-1 serving
Recommended Daily Consumption for Adult Men who Choose to Drink Alcohol: 0-2 servings
One serving of alcohol is: 12 ounces / 250 ml of beer, 5 ounces of wine / 150 ml, or 1.5 ounces / 45 ml of distilled spirits
Calories per Serving: 100-200
Level 6: Caloric, Sweetened Beverages without Nutritional Benefits
Recommended Daily Consumption: 0-1 serving (8 ounces / 240 ml)
Calories Provided per Serving: 75-130
 Valtin, H. “Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 x 8”? Am J Physiol Regul Integr Comp Physiol 283: R993-R1004, 2002.
 Popkin, B, H. etal., A new proposed guidance system for beverage consumption in the United States. Am J Clin Nutr 83: 529-42, 2006.
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