Month: October 2011

Top 10 Nutritional Myths

This article is taken from the ebook “Nutrition: The Basics & Beyond”. For the full ebook, visit the TBS Store.

Don’t drink alcohol. Avoid eating eggs. Eating carbohydrates late at night makes you fat. We’ve all heard these pieces of nutritional advice for years – but just how accurate are they?

10. Eating carbohydrates makes you fat.
Cutting carbs from your diet may have short-term weight loss benefits due to water loss from a decrease in carbohydrate stores, but eating carbs in moderation does not directly lead to weight gain. The body uses carbs for energy, and going too long without them can cause lethargy. The notion of cutting carbs out of your diet exclusively comes from diets such as The South Beach Diet, The Atkins Diet, The Zone Diet and calls for zero carb intake. Many people have lost weight using these diets. The problem is that using fat & proteins as your source of energy for prolonged periods of time is unhealthy and dangerous. Ketones are by products of protein synthesis and have a low pH level. Increasing their presence within the blood stream will cause the blood to become acidic, leading to Ketonic Acidosis. Moderating carbs, cycling carbs & even minimising carbs for short periods of time can be very beneficial and are concepts that Ii regularly utilise for photo-shoots and also for clients, whether they are looking to lose weight for general health or for competition. However, carbohydrates from healthy sources, with a good amount of fibre are not only beneficial in health terms, but will also help with weight control.

9. Eat frequently to maintain your metabolic rate.
In the section Energy Expenditure we talked about the Thermic effect of food (TEF). Each time you eat, metabolic rate increases slightly for a few hours.  It also takes energy to break down and absorb energy. However, the amount of energy expended is directly proportional to the amount of calories and nutrients consumed in the meal[1]. So if you eat a large meal, the amount of energy expended would be large, but would then taper off over time.  If you were to eat the same amount of calories, split up over 2 meals, the energy expended would be exactly the same, except the peak in energy expenditure would be lesser and over a lesser period for each smaller meal.  It is more about total calories and the ratios of macronutrients, than the size of the portions ingested.

8. It is better to eat 5-6 smaller meals to control your hunger.
This statement is something we have often heard & still seems prevalent today.  Yet, despite so many people living by this notion, the amount of research supporting this, is scarce at best.  Of the studies alluding to this theory, many have involved clinically obese subjects [2], & the application to the real world environment is less than appropriate [3]. In fact, recent research suggests that eating 3 larger meals is more beneficial than eating more frequent smaller meals.  Above all, meal frequency is individual and takes into account things such as appetite, lifestyle and daily routine.  Current research with a normal meal pattern and protein intakes that are closer to what can be seen in a typical diet, suggests superior appetite control when eating fewer and larger meals [4].

7. Eating 5-6 smaller meals control blood sugar levels.
We are not so different to our caveman ancestors, granted, the majority of us have a little less body hair, but from a biochemical perspective, little has changed.  Back in caveman times, balancing your blood sugar levels over the day was not exactly high on the priority list, more chucking spears at woolly mammoths  & sabre tooth tigers.  You couldnt just grab a bite to eat from the fridge.  People seem to believe they will suffer severe hunger and mental impairment from not eating every so often, in fact ive heard bodybuilders and fitness models complain Im running on empty, I feel so weak just because they havent had a meal in 2 hours!  Maintaining blood sugar is a priority, as we discussed in the Macro Nutrients section.  However, because of this, the body has developed efficient pathways that will make it happen even under extreme conditions. If you were to fast for 23 hrs and then go for a 90 min run at 70-75% VO2max, your blood sugar after the run would be identical to the same run performed after eating a meal. It takes at least three days or 84 hours [5] of fasting to reach blood sugar levels low enough to affect your mental state and even this is temporary, as your brain adapts to the use of ketones. Studies have shown that during 48 hours of fasting, or severe calorie deprivation, blood sugar is maintained within a normal range no measure of cognitive performance is negatively affected [6].

6. Fasting causes the body to go into starvation mode.
To say that missing a meal here & there can be classed as starvation is not only incorrect from a biological perspective, I actually find it offensive when there are people in developing countries that truly are starving.  If we go back to the caveman ancestors I mentioned above, adaptation was a very important key to survival.  The lowering of our metabolic rate in times of starvation was how we survived.  But this is when the term starvation actually meant just that, not skipping a meal for 24 hours!  Looking at experiments studying the effects of starvation, the earliest responses found from a metabolic sense occurred after 60 hours [7]. That is nearly 3 days!!  Other studies debunk the myth even further, showing that metabolic rate is actually increased in short-term fasting [8,9]. So next time youre stressing because you havent eaten for 3 hours, maybe you are actually doing your body a favour!

5. The body can only absorb 30 grams of protein in one sitting.
Once again, we return to our caveman ancestors to debunk a myth which has somehow invaded the bodybuilding & fitness fraternity and remained for far too long.  Ask yourself the question, if we were only able to absorb 30 g of protein in any one meal, how would our ancestors of tackled the large amounts of protein in mammoth steaks (literally!)? The simple truth is that more protein just takes a longer time to digest and be utilised. Studies have shown that the digestion of a standard meal is still incomplete after five hours, amino acids still being released into the blood stream and the body still anabolic[10]. This common misconception regarding protein intake is based upon a study done by Boirie (1997)[11],  this study found that 30 g of whey protein was ingested in 3-4 hours.  Unfortunately many took this to mean that, to maintain a positive nitrogen balance, 30 g of protein must be ingested every 3-4 hours, which is not what the study demonstrated.  The subjects in this study ingested the protein fasted, meaning there was no delay in the digestion of the protein used in the study.  Also, whey protein was used.  Whey is a fast acting protein (see Macro Nutrient section), being digested faster than any other protein source at 10 g per hour.  When combined with other food stuffs, such as fats, the digestion becomes slower.  Casein protein, the slow acting protein we discussed in the Protein section is digested much slower (in fact in Boiries study, it was still being digested at the end of the experiment, 7 HOURS later!).

4.  Eat protein every 2-3 hours to maintain positive nitrogen balance.
This myth is based upon the same rubbish from the statement above.  As people believed that you were only able to absorb 30 g of protein at any given time, you must take on another 30 g 3-4 hours later, otherwise you would be running on empty.  As I explained earlier, it can be all too easy to take a study and interpret the results incorrectly.  This myth is complete and utter rubbish & the sooner everyone realises it, the better!
Dont be like Batman or The Rock!

3. Skipping breakfast is bad and will make you fat.
This argument has been made popular by many cereal companies (I wonder why??) & one large study is often referred to, to back up such claims [12].  Unfortunately, the only results that particularly study shows, is that people who eat breakfast seem to have better control over their dietary intake and are less likely to eat over their calorific needs overall, than those that skip breakfast and then subsequently pig out on high sugar, high fat foods.  Ministry of the bleedin obvious or what? Another argument that is made for not skipping on breakfast is we are more insulin sensitive in the morning[13], this is true. But then you are always more insulin sensitive after an overnight fast. Or rather, you are always the most insulin sensitive during the first meal of the day!  Insulin sensitivity is increased after glycogen depletion and if you haven’t eaten for 8-10 hours (recommended duration of sleep), liver glycogen is modestly depleted. This is what increases insulin sensitivity – not some magical time period during the morning hours.  This is also the case with resistance training. Insulin sensitivity is increased as long as muscle glycogen stores aren’t full, which is typical after a 1 hour session of PT with me!  It doesn’t disappear if you omit carbs after your workout.

2. If you train on an empty stomach, you’ll lose muscle and have no strength.
This statement is based upon research done on sports performance during fasting periods such as Ramadan, using aerobic exercise [14].  The problem with this type of research is that, when taken out of context, people will be misinformed.  As we discussed in the Water: Importance of Hydration section, dehydration can lead to a serious drop in performance (just 5% dehydration can lead to a 30% drop in fact).  Fluid restriction will cause a drop in performance, as was shown in the study above, this is proven.  However, the majority of us should be taking on enough fluids to compensate for any losses due to exercise, not something that can be done in a study relating to Ramadan!  It is also worth mentioning that those participating in weight training, an anaerobic form of training, are not effected in the same way as the subjects in the Ramadan study [15] .
Studies have also shown that lower intensity exercise and strength training, without fluid restriction are also unaffected, even after 3.5 days of fasting [16]. This is further supported by recent research on fasted training [17].

1. Eat breakfast like a king, lunch a queen, dinner like a pauper.
In a way, this myth is also related to another outrageous belief that eating carbohydrates late in the evening will turn you into a toad.  Ok, not quite that, but if you were to proclaim that you had finished your evening workout and were now off to eat a couple of jacket potatoes, the gasps of shock & disbelief you would be met with would be deafening!  Where the notion of post 6pm carbs = food of the devil is anyones guess, but it probably comes from the idea that any carbs you dont use straight away are stored as fat.  A sound concept, to a point, yet easily debunked nonetheless.  Earlier I mentioned that the total amount of calories you ingest over the day is the most important thing in terms of the TEF.  Well, the same is applicable when it comes to the times you eat.  If you have fasted throughout the day and then eat a meal high in carbs late in the evening, your body is not going to store the calories ingested as fat, whether they are sourced from fat, carbs or protein, unless you are eating above the amount required.  Studies relating to those observing Ramadan have shown favourable changes to body composition when feasting at night after a day of fasting [18]. Also, if maintaining muscle is your goal, you may be interested to learn that a study comparing subjects eating a large breakfast to those eating a large meal late in the evening showed those eating earlier in the day lost more weight than those eating later. However, the loss in weight was due to a drop in lean mass (muscle), with the later eaters maintaining their lean mass [19].

For information regarding references, further chapters mentioned or if you would like further information, please use the contact page on the website.  “Nutrition: The Basics & Beyond” ebook is available on the TBS Store for a special introductory price of £8.99.