NutritionEd:

“What should I eat before I work out?”. If you’re like me, you ask yourself this question every time you go to the gym. And if you’re TRULY like me… then you probably don’t have a definite answer. It seems rather intuitive that one should eat a high energy meal before you work out because you will need it during your exercise. But what should you eat if you are exercising to lose weight? To answer this, we must first look at something called the glycemic index of food.

Briefly, the glycemic index (GI) is a system for understanding the relative glucose (sugar) response a certain food will impart in your blood. A high glycemic index food will result in a more pronounced “spike” in blood glucose than will a low glycemic index food. Such a spike has various metabolic consequences; some of which affect the body’s ability to burn fat. The GI system was originally designed for people with diabetes in order to help them control their blood sugar when they eat foods containing carbohydrates (aka “carbs”). However, in recent years the concept has been expanded to numerous other fields including weight management.

For many years, researchers have known that, for men, eating a low glycemic index meal before you work out will result in a higher rate of burning fat than if you ate a high glycemic index meal with the same macronutrient profile (i.e.: carbs, protein, & fat). A recent paper in the American Journal of Clinical Nutrition has now confirmed that this is also the same for women.

What is it about the low glycemic meal that results in this increased rate of fat oxidation? The answer is rather complex but part of the responsibility lies with the remarkable hormone insulin. Insulin is what’s called an “Anabolic” hormone meaning it promotes the synthesis of many components the body needs for life. It is also closely tied to the storage and utilization of energy. When your body has a high amount of glucose in the blood (aka blood sugar) insulin is responsible for promoting its dispersal throughout the body in order to provide energy to cells and subsequently bring blood levels down to normal. However, if the body doesn’t need energy then it will revert to storage mode and convert glucose into fat which is then directed into fat cells by, you guessed it, insulin. Voila, your fat mass will increase.

Now, don’t let this turn you into a low-carb crazy person! I’m actually working on another post regarding low-carb diets and their pitfalls so stay-tuned. The above information is merely meant to explain the actions of insulin in response to a normal meal and how eating a high glycemic food before exercise will cause your blood sugar to dramatically rise and your body’s “desire” to burn fat will subsequently be impeded. Therefore, on the flip side, if you eat a low glycemic meal then your body will not be as inhibited to burn fat and your exercise will be more effective at helping you lose weight. And to burn even more fat, research has shown that drinking skim milk, as opposed to an energy drink, immediately after resistance exercise can encourage muscle gain and fat loss. Who needs supplements eh?

If you are interested in learning more about the GI index click here. This site provides a more thorough description of the GI concept and also lists many foods which are deemed high or low glycemic foods.

As I recently posted, there are many things to consider when choosing an oil to use at home. In my post I mentioned olive oil as being a wise choice for use in many applications because it has a unique texture and flavour, it is composed of a healthy proportion of monounsaturated fatty acids, and there are some varieties which are fairly stable when heated.

Further to this, I’ve found a report published by the Mayo Clinic which extols more specific advice. The report offers tips on choosing which variety of olive oil is best such as:

1. If you’re not cooking with it, choose virgin or extra virgin olive oil because it is the highest in antioxidants
2. Choose oil that has been packaged most recently (no more than one year old) because vegetable oil, of any kind, will decay and become rancid over time (although olive oil is more stable than others if kept in a cool dark place)
3. Choose the price that fits your lifestyle. Olive oil can vary widely in price yet yield little discernible difference in texture and flavour.

One small caveat, if you are cooking and you insist on using olive oil, try to use light olive oil instead because it has a higher smoke point than virgin and is therefore more stable. There’s not much point using high antioxidant virgin olive oil if all you are doing is degrading it into the very product you want to neutralize in your body; free radicals. Honestly, however, the use of canola or grapeseed oil would be preferred for high temp cooking. Why not have both available in your cupboards? Just remember to store them appropriately (olive oil in the dark, grapeseed in the fridge)

Found some interesting news about Vitamin K on a blog I stumbled across by Marc Joseph. Reading it really makes you ask yourself, “Do I eat enough vegetables?”. His post references a recent paper in the journal Thrombosis and Hemostasis regarding vitamin K and how deficiencies in people may be much more common than previously thought. The key term here is actually “sub-clinical” deficiency which essentially means you present with no clinical symptoms or indications of malnourishment yet low levels in the body are nevertheless having a deleterious effect; which may result in symptoms later in life.

I’ve usually associated Vitamin K with the clotting mechanism in blood but it is also important in bone maintenance and cardiovascular health. Having a chronic sub-clinical deficiency may increase your risk of developing various conditions such as osteoporosis or calcification of blood vessels (which can lead to heart attack and stroke).

Chalk up one more reason to eat your leafy greens, eh?

It’s great to see posts like this one recently blogged over at NutritionData.com. Salt (and more specifically sodium or Na) is one of my nutritional pet peeves. The nutrient is so pervasive in our N. American diet and has been for decades. Thanks largely to our obsession with eating highly preserved foods, people classified as “salt sensitive” are highly challenged when adopting a “low-sodium” diet (1-2g of sodium per day). Indeed, even for the average person it is difficult to not exceed the RDA (recommended daily allowance) of 2.3g/day. To that end, many clinicians adopt a more conservative approach and advise a “No-Added Salt” diet which includes 2.3-4.0g/day; something that I personally follow.

If ever you’re concerned about your Sodium intake the first thing you should do is consult the nutrition facts table on any food item you buy. The more likely high-salt culprits are:

• Anything that is canned (soups, sauces, beans/lentils/corn etc)
• Frozen meals (pizza, single serve meals)
• Junk food (chips, pretzels)

See anything familiar? Most of the items listed above aren’t particularly good for you anyway; regardless of salt content. However, the insidiousness of Sodium is seen when you look at healthy foods such as canned vegetables/legumes. Here salt is again used as a preservative (very necessary) but can be easily rinsed off (recommended) prior to using. Further, Sodium isn’t just found in items that contain salt. For example, the preservative Sodium Benzoate is quite often used in items such as Soy Sauce or BBQ sauce. That’s why I recommend always looking at the Sodium content itself and ignore any messages on the label that claim “Salt Free”.

Lastly, even if you aren’t classified as “salt sensitive” you should still be aware of how much Sodium you consume. Recent research is indicating that diets high in Sodium and low in other nutrients such as Potassium may increase the risk of hypertension. Therefore, as with Omega 3 and Omega 6, it is important to achieve a good ratio of Sodium : Potassium in your diet. No specific recommendations on this ratio exist but you can always just follow the RDA in order to be satisfied the ratio is acceptable. For your reference, the RDA for Potassium is 4.7g/d.

Every now and then I hear the terms “Good” and “Bad” cholesterol being bandied about. When I hear this it causes a little nerve in my head to go “ping!” and I get mildly discombobulated. It’s like the media has played up HDL to be the mild mannered vascular hero of the 21st century and LDL the sinister villain that needs to be defeated. In reality, LDL has a very valid and necessary function in the body and only when levels get too high are we presented with a “Bad” situation.

LDL (low density lipoprotein) and HDL (high density lipoprotein) serve as carriers of cholesterol (and other molecules) throughout the body. They work in somewhat of a cycle, with LDL traveling out from the liver dispersing its contents as it goes, and HDL acting like a sieve and collecting cholesterol on its way back to the liver where it can be broken down or reutilized. See? No harm in that is there? It’s only when the concentration of LDL exceeds a certain point (>4.1 mmol/L) and/or HDL drops past a certain point (<1.03 mmol/L) that we should be concerned about our health.

Now, don’t let my little post here mislead you into thinking LDL isn’t that big of a problem. It definitely is, because when you have chronically high LDL circulating in your blood you are at increased risk of developing atherosclerosis which can lead to heart disease and stroke. This is serious business.

Further, if you are young, don’t disregard this as not applying to you. Research has found that atherosclerosis can start developing in your early teens. And with the childhood obesity epidemic continuing unabated we are now finding children with high blood pressure. Children! On blood pressure medication! The ramifications of this are incredible. So in short, you are never too young to be concerned about the health of your heart… or your blood vessels.

With the plethora of choices available on the market today it can be hard to choose the most appropriate cooking oil to buy. What most people don’t know, however, is that the aesthetics of oil (taste, texture etc.) are only part of the equation when it comes to choosing the product which best suits your needs.

Not all oils are created equal

There are two issues that you must be aware of when purchasing cooking oil:

1. What is the intended use

1. What is the nutritional content

Intended Use

Something you may not be aware of is that cooking oil has varying degrees of stability to heat. If the oil gets too hot, it begins to break down into both unappetizing and unhealthy by-products. However, there are some varieties on the market which are superior for high temperature cooking such as for stir-frying. (if you’re asking which oil is good for deep frying then you should be ashamed!). The stability of oil when heated can be gauged by it’s Smoke Point. Basically, the higher the smoke point the more stable the oil is. Of course, if you are using the oil in a way that does not involve heat (such as in a salad dressing) then the smoke point is irrelevant and you can move directly to point #2.

Nutritional Content

The oil you buy at the store is composed primarily of Triglycerides. Within this there exist (amongst other things) 3 different types of Fatty Acids. These fatty acids are differentiated into:

• MUFAs (monounsaturated fatty acids) such as Oleic acid

• PUFAs ( polyunsaturated fatty acids) such as Omega 6 and Omega 3 fatty acid

• Saturated fatty acids such as in lard or animal fats (in my opinion you should avoid using animal based fats for most applications, though butter is excellent for some recipes)

Everyone (hopefully) is by now aware of the dangers of a diet high in saturated fat… so lets not go there! What you may not know, however, is that recent research indicates the amount and types of PUFAs or MUFAs we consume, such as omega 3, can directly affect our risk for cardiovascular disease. Further, the ratio of PUFAs to MUFAs in our diet may also have an effect on our heart. Unfortunately, the average North America diet contains both an unfavorably high PUFA: MUFA ratio and is LOW in it’s omega 3 content. (~20:1). At this time the debate continues as to what the ratio of PUFA to MUFA in our diet should be; but a good goal is ~8:1. And if you are looking for products which contain omega 3 fatty acids, the options continue to grow. You can even find it in some milk products now! The key question though is, “Do these new products contain physiologically significant amounts?” That’s an entirely different topic, however, but if you’re interested I would be happy to discuss it.

Overview

So, in light of the above information the oil you purchase should be:

• One that has a relatively high smoke point (if you are cooking with it)

• One that has a high proportion of MUFAs and/or is high in omega 3 fatty acid

One of the most stable cooking oils is Grapeseed oil, something I have personally been using for years. In addition to it’s high heat stability, Grapeseed oil offers a relatively neutral taste and so the natural flavours of your food won’t be masked when cooking with it. However, the downside of this product is that it is contains a high proportion PUFAs. A better choice may be olive oil, which is rich in MUFAs (don’t you just love these acronyms?).

Although it would be ideal to have a few varieties on hand for different applications, you can get by reasonably well with just one variety.

Click HERE for a summary of cooking oils. This great wiki provides details such as what types are available, comparisons on respective saturated vs unsaturated content, and their smoke points.