Body Temperature: a Metabolic Thermostat

Ilana Katz MS, RD, CSSD


It seems the climate in most areas is a topic of conversation these days. It’s not that we are making small talk with weather conditions, but the unusual climates are setting in. Freezing way before winter starts, or a few hot days emerging in the midst of a cold spell, and vice versa for Summer. So how does a cyclist (or endurance athlete) know how to dress, or even eat accordingly, when they could experience four seasons in a matter of hours. In this article I intend to address how temperature changes ones metabolism, and if you as an athlete can use varying nutrition to take the most advantage of what Mother Nature has to offer.

As body temperature increases, so does metabolism. Thus temperature and metabolism become directly related and metabolism itself is directly affected  by all daily living components, that is eating, sleeping, exercise and physical exertion.

Body Temperature and Metabolism

Working muscles cause the internal body temperature to increase. The physiology of blood transporting oxygen as needed  and removing the byproduct requires the metabolism of calories, or as we know it, food energy. This further translates into the more activity, the higher the body temperature, and the ultimate requirement an increase in the metabolism of more calories. So the question becomes what happens in cold weather. A cold body temperature decreases the chance of burning more calories. So one would think that  if you have not dressed warmly enough for a long ride in winter, you may jeopardize your chances of burning calories. Actually, the opposite is true, and here is a good time to introduce the difference between internal and external body temperature. Internal body temperature will rise when a body is active, this is a given. When externally the temperature is extremely cold, physiology takes over to ensure the internal temperature is safe and warm, hence the effect of shivering. Simply put, movement of bones and muscles become involuntary to generate heat. So how does food choices on a long ride effect this, actually very little. The important thing is the cyclist is giving the body enough food to provide the fuel the metabolism is demanding.

Types of Metabolism and Body Temperature

Most of the calories burned on a daily basis actually takes place during resting periods, also known as basal metabolism. Basal metabolism includes all of the body’s natural functions required to sustain life. The basal metabolism varies from individual to individual, typically affected by health conditions, body composition and body temperatures.

Through your cycling efforts, more calories become metabolized due to the increase in the body’s temperature through working muscle tissue. Calories required for this and other physical activity account for some of the calories needed for basal metabolism, but not as many as most people think. In other words, if you catch yourself allowing a feast fit for a king because you rode a couple of hours, you may be missing the point, especially if you are trying to get leaner. For an optimal burn in fat, not every calorie needs to be replenished post work out, and furthermore, the body has a lot more potential to store calories (stored calories = fat) as it becomes more of an efficient machine. Aerobic endurance (which cycling certainly is) has the potential to teach your body to become efficient, which also means, you would require less fuel to get through the same ride today, as you did a year ago.

The amount of calories metabolized through exercise and muscle exertion does however increases the body’s basal metabolism over time, and certainly temporarily after a long ride. But remember basal metabolism, is different to the fuel needed for during a long ride.

There are many calorie calculators (apps and online) that can give you an average caloric burn per hour. But be warned, these calculators are all basing the calculations on the middle of a bell shaped curve (average) of what you enter in to them.  For example the amount of caloric burn for an average size male (170 lbs)  riding at about 16 – 18 mph is about 800 calories. My point is, there is no way the calculator can know where this individuals basal metabolic rate lies, what his muscle mass versus fat mass is, if he has a history of long consistent endurance training or is a newbie – all these factors, and more, affect this calculation.

There is a silver lining even as we become metabolically efficient, and that is that merely just eating and digesting food,  the body metabolizes some extra. This natural process, often referred to as the thermic effect, increases through the process of eating healthy foods and remaining active. Dehydration and excessively decreasing body temperature reduces the body’s ability to digest food properly.

Muscle Demands

Both muscle strengthening (resistance exercises) and aerobic or cardiovascular activities such as cycling, increase body temperature and break down muscle tissue. In order for muscles to grow and repair broken down fibers, the muscle tissue requires calorie metabolism in order to carry out the functions. This is a continual process which has further demands on the metabolism to work hard consistently, even at rest. In other words, during sleep, muscle groups continue to repair. This is a great physiological explanation of why breaking down and repairing muscle with the correct recovery nutrition increases ones metabolism. In other words, that same 170 lb male in the example above, may actually burn 1000 calories versus 800 per hour cycling, if he has more lean muscle and less fat.

In Summary

The human body regulates internal temperature in order to maintain a steady rate in which normal functions occur. As mentioned above, during the winter or in a very cold room, a human will normally shiver. This natural process represents the body fighting in order to keep muscles warm and the body temperature stable. The direct opposite of this situation, when external temperatures become extremely hot or even warm, the body sweats in order to keep the body cool. This process does not increase metabolism and neither does shivering, simply because neither of the two raise or lower body temperature, but rather fight to maintain a stable rate. Therefore it is irrelevant as to what the temperature of the food you are eating on the bike, in hot or cold extremes, as long as the food is fuel to compensate the metabolic burn rate.

Hyponatremia: Signs, Symptoms and Warnings

Ilana Katz MS, RD, CSSD

Hyponatremia tends to be mostly associated with athletes who participate in long duration sports such as marathons and triathlons. Endurance athletes taking in water during training or an event can develop hyponatremia, a potentially life threatening condition that occurs when sodium levels drop to a dangerous low in the blood stream (below 135 mmol/L (of blood). Early symptoms may include nausea, drowsiness, confusion, headache and fatigue. These can quickly progress to seizures, coma and death if not resolved in time. Importantly, athletes are not the only population that needs to be aware of this deadly phenomenon.

Dilution of sodium can result, as mentioned, from over-drinking, but also from water retention (often a side effect of various medications). Sodium can be lost in various ways other than dilution which include urination, perspiration and gastrointestinal distress (vomiting/diarrhea). Furthermore certain medical conditions such as congestive disease, kidney dysfunction and ineffective ant-diuretic hormones are known causes.

Since hyponatremia has usually been associated with endurance sports, those who engage are much more well-informed than in the past, and emergency staff who treat athletic stress conditions are also far better educated to recognize and manage symptoms, and even play a role in prevention. The sports medicine community has been helpful in raising awareness about risks and signs of over-hydration. However, with obvious evidence that there are many other populations at risk for hyponatremia, it is vital to recognize these so that all health care professionals are on the leading edge of avoidance and if necessary, acute care.

Some examples of patients who may be eligible for high alert:

  • Psychiatric patients with a syndrome known as psychogenic polydipsia, meaning they drink excessive amounts of water..
  • Multi-pharmocological patients (especially elderly). Why, well because many medications have potential risks.
    • Diuretics deplete electrolytes, including sodium
    • Antidepressants increase level of antidiuretic hormone
  • Patients being administered intravenous hypotonic fluids: hypotonic fluids contain a lower concentration of sodium than blood and thus excessive quantities at high entry rate can dilute sodium.
  • Tube fed patients: proper fluid levels and electrolyte balance must be continuously monitored and orders adjusted based on results of consistent blood work.

There is also the all controversial sodium debate to consider. Researchers and health practitioners often have opposing arguments as to whether dietary sodium should always be strictly conserved. While lowering sodium is unarguably beneficial for those already diagnosed with hypertension (high blood pressure), increasingly conservative recommendations for the average population is often contested. The argument being that too little sodium can lead to other health problems, the main one being hyponatremia. Interestingly, the dietetic community are in agreement that avoidance of dietary sodium is unlikely to cause hyponatremia. Even a very low sodium diet of 500 – 1000 mg/day should maintain adequate levels under normal circumstances. It is the complexity of what defines “normal circumstances.”

In summary, with regards to controlling appropriate levels of sodium in the blood and avoidance of hyponatremia, not only athletes should be aware of hyponatremic signs and symptoms. For those with a normal blood pressure, eating patterns and water intake should be developed based on clinical judgement, guidelines and scientific evidence.

glass of ice blue





One of my biggest challenges, not only with my own personal goals, but also with many clients, is to get to the bottom of the age old obscurity of sugar cravings. It’s not rocket science, right? Just don’t eat it ! Right? But oh we all know it, and live it day after day, it is just not that simple.  Why? Because the physiological response to sugar is like an addiction. Sugar temporarily elevates the levels of various neurotransmitters and endorphins. The “feel good” chemicals, serotonin and dopamine are released when sugar is metabolized, giving a sense of pleasure.  Sugar cravings therefore, are best explained as an addiction to endorphins which is a reaction similar to the high of a drug addict.

So is this addiction a serious or dangerous for that matter?  The answer is both yes and no. Our bodies do need sugar. The required fuel for the brain, is in fact glucose.  The metabolism can thus effectively metabolize what we eat and provide the energy source required thereof.  The key phrase here is “amount required.” The danger takes effect when the amount of sugar that is consumed is way more than required for the optimal source of energy. Furthermore, sugar that is refined has no nutritional value resulting in empty calories. Calorie dense yet nutrient free foods if make up most of ones diet, will lead to an array of health problems from overweight and obesity to diabetes and cardiovascular disease, just to name a few.

As noted, sugar is used an energy fuel which is needed by the brain. The down side is that it causes blood sugar to rise, and as quickly as it rises, it plummets back down, resulting in the physiological need for more sugar to get it back up, and the vicious cycle of craving sugar begins. It is like a rollercoaster set in motion, swinging from hyper to hypoglycemic reactions (a pendulum of high to low blood sugar levels). This is the body’s homeostatic response to stable blood sugar, in other words, trying to keep the body in balance. Unfortunately the physiological overcompensation is what causes our uncontollable cravings.

This does not mean to say that you should be on a low carbohydrate plan to avoid cravings, in fact, it is quite the opposite. For one thing, it has already been stated that the required fuel for the brain is carbohydrates in the form of glycogen, so avoidance of carbs is unhealthy in itself. It is it the amount of carbs that is relevant, as well as the type of carbohydrates eaten, that will reduce sugar cravings.

Trying to cut calories by reducing carbohydrates tends to increase sugar cravings.  Sugar substitutes like Splenda and sugar alcohols are use by manufacturers to enable them to market lower sugar or lower net carbs on the label seemingly offering a more attractive product for dieters. Be wary – firstly the jury is still out on the long term safety of these substitutes. And secondly, sugar alcohols have been found to actually have a negative effect on blood sugars. We are then back to square one; the pendulum swing in blood sugar in a day is what leads to the vicious cycle of cravings, trying to satisfy them with foods that trigger and result in more cravings.  In other words, sweet things make you want to eat more sweet things, and although artificial sweeteners are calorie free, they are not helping with reduction in cravings whatsoever. Furthermore, sugar alcohols have a tendency to cause gastrointestinal distress in that they induce diarrhea and flatulence.

Net carbs is also a marketing “con” so to speak. Supposedly, net carbs, a term coined by Atkins Nutritionals, is defined as the net value of carbs once fiber has been removed. According to the Food and Drug Administration, there is no such value: carbohydrates are carbohydrates, whether they are made up of refined sugar, starch or fiber, and every gram of carb has four calories.  So do not let low carbohydrates fool you in your endeavour to reduce cravings. Manufacturers have simply replaced regular carbs with sugar alcohols and sweeteners.

Craving sweets is often an indication of a deficiency in certain nutrients. Chromium, carbon, phosphorus, sulphur and tryptophan are often the culprits and eating a rainbow of color is a simple solution.  Broccoli, grapes, legumes and chicken (chromium), Fresh fruit (carbon), fish, eggs, legumes and chicken (phosphorous), cranberries, cauliflower, kale and cabbage (sulphur) and turkey, liver, lamb, sweet potato and spinach (tryptophan).

One last point on preventing the energy swing which is the main culprit of sugar cravings has to do with timing of intake. Waiting too long to eat or grazing all day (not waiting long enough to eat) has a similar effect to that hyper and hypoglycemic response mentioned earlier. It is during the steep peaks and valleys in energy that one feels lethargic and emotional. At these times the physiological response is to eat sweet things. Furthermore, we justify allowing ourselves to eat the treats and sweets that stimulate a pleasurable response, with stress and emotions (as if we deserve the pleasure). This only leads to guilt and depression. Evening out the peaks and valleys is the solution to curb those debilitating cravings.

In summary, the details thus far reflect on the amount of carbs, sources of carbs and timing of meals in combination as a solution for erasing sugar cravings. Practically worded, eat fresh fruits to satisfy a sweet tooth, get the refined sugars out of the body to aid in stable blood sugars,  avoid high sugar or processed products, like candy, soda, fruit drinks, pastries, etc., replace the “processed” products with foods that come from the earth (grains, legumes, potatoes)  and avoid artificial sweeteners. Make sure you get a rainbow of color in your daily intake. All the colors found in fruits and vegetables represent the vital vitamins and minerals that if lacking, will stimulate cravings.


Gluten is the protein in wheat that has received much attention in the media lately. I get many questions on whether or not it is an option worth choosing.  I am thus dedicating this newsletter to some interesting facts, tips, recipes, and tid bits on gluten, to hopefully help each individual decide. It is a lifestyle choice, and it is not always simple!

“Should I Go Gluten Free?”

One of the latest trends is a gluten free diet with an increasing variety of GF products available in grocery stores and restaurants. However, does that mean you should cut gluten out of your diet? Whole grains are an important part of a balanced diet with many nutritional benefits yet more people are avoiding wheat, rye, barley, oats, and anything that doesn’t say gluten free on it. Gluten is a protein that provides elasticity in dough to give bread and other products a wonderful texture. So, why give that up?

It is currently only recommended to eliminate gluten from your diet if you have a gluten sensitivity/intolerance/allergy or Celiac disease. A gluten free diet can be restrictive in both choices and nutrients.  Some drawbacks of a gluten free diet include an imbalance of intestinal flora (the bacteria in your gut which protect or harm your GI tract, depending on the bacteria, and can also influence weight gain/loss), lethargy, vitamin B deficiencies, calcium deficiency, and other documented conditions. With that being said, there are a number of individuals who tout the benefits that they have personally experienced having cut out gluten from their diets such increased energy levels and weight loss. With any diet, it’s important to get adequate nutrients and calories and restrictive diets can be challenging in that aspect.

Gluten sensitivity and Celiac can be diagnosed in a variety of ways. Keeping a food diary that tracks your mood and symptoms as well as foods can help you and a health professional better assess if you do have any issues with consuming (or even touching) gluten products. Some individuals eliminate gluten from their diets during a short period of time, as well, to see if gluten causes unwanted symptoms when re-introduced to the diet. An important piece of information to remember when attempting to be diagnosed with a gluten sensitivity or Celiac often includes consuming gluten so the presence of it is in your system during testing, depending on the diagnostic tool.

If you’re avoiding gluten, you will want to check the ingredient  and nutritional labels for:

  • Certified Gluten Free
  • 100% Gluten Free
  • Wheat
  • Wheat gluten
  • Barley
  • Rye
  • Oats: do not necessarily contain gluten but many with a gluten sensitivity have trouble digesting oats as well.
  • Malt
  • Hydrolyzed vegetable protein

What can you eat instead?

  • Corn; including cereals and other corn-based products
  • Rice; including cereals and other rice-based products
  • Potatoes
  • Craving pasta? Consider using spaghetti squash instead
  • Wine is generally safe but check the ingredients to be sure
  • Eggs
  • Fish
  • Dairy
  • Meat
  • Fruit
  • Vegetables
  • Specialty, GF products



Fitness Corner: Yoga

Yoga, once a male-dominated practice, is being done by people of all ages, genders, at home, at the gym, and in the park. It has extraordinary benefits for the mind and the body. Would you consider trying it? If so, you will want to try out a variety of styles (some people love flow yoga while others love power yoga and others simply prefer a different style) and teachers as no one yoga instructor is like another.

The benefits?

Increases strength. That’s right- you can see some amazingly toned yoga bodies using their muscle strength to hold astounding poses.

Increases flexibility. Not only are certain muscles being strengthened during a pose, others are being lengthened.

Improves posture. Yoga poses focus on a straight back so lots of practice can make perfect!

Provides relaxation through meditative breathing. Now that’s a way to pack a punch- get in shape and get rid of stress at the same time!

Relaxation, proper breathing, increased muscle tone, movement that increases circulation, and other benefits of yoga also benefit the heart.

Yoga may also be beneficial for memory loss, concentration, and even IBS symptoms in some individuals.

Yoga is not to be treated like a race or performance. You go at your own pace. You choose your level of intensity and hold the pose as long as you comfortably can. If you are interested in trying yoga, fitness centers offer classes that may be beneficial to beginners as instructors can help make sure poses are done properly for your own safety. Want to try it for free? Consider a free video online from or to see if yoga is right for you.



Cinnamon Up Your Life
Cinnamon is a very common spice that has recently received a pat on the back because of its health benefits. There have been many studies discovering its effect on glucose metabolism, antiseptic powers against bacteria’s and fungi and even for improving brain function.
Some of the possible ways in which one can enjoy this power spice:
– Add a cinnamon stick to flavor your favorite tea
– Add to unsweetened applesauce, cereal or oatmeal
– Sprinkle on toast or add to butter or cream cheese
– Sprinkle on coffee, cocoa, fruit juices, and ciders
– Add cinnamon to your favorite baked goods
Remember after opening your cinnamon store it in a tight sealed container away from the light.


If you’re looking to add some different spices to your life, consider this recipe:

Recipe Corner: Curried Red Lentil Soup      (SERVES 6)

  • 1 cup hulled red lentils, rinsed in hot water
  • 4 1/2 cups nonfat vegetable stock
  • 2 Tbs. nonfat plain yogurt
  • 1 tsp. curry powder, or to taste
  • 1 tsp. grated fresh ginger, or to taste
  • 1/2 tsp. ground cumin, or to taste
  • 1/4 tsp. cayenne, or to taste
  • 1/2 tsp. onion powder, or to taste
  • Shredded coconut as garnish
  • Dried peanuts as garnish
  • Cilantro leaves as garnish
  • Diced red pepper as garnish
  • Chutney as garnish
  • Raisins as garnish


  1. Put lentils and vegetable stock in a large saucepan, and bring to a boil over medium-high heat. Reduce heat to medium, and cook for about 20 minutes, or until lentils are tender. Reduce heat to very low.
  2. Put 2 cups lentils and yogurt into blender and purée until smooth. Recombine with soup in pan, and stir in seasonings. Heat through, and serve, garnishing each portion as desired. 


Calories 130
Protein 8g
Carbs 25g
Sodium 520mg
Fiber 6g
Sugar 5g




  • 1   cup uncooked quinoa
  • 2   tablespoons fresh lemon juice2   tablespoons olive oil
  • 2  tablespoons chopped fresh basil
  • 1  can (15 oz) gluten-free garbanzo beans, drained, rinsed
  • 1  can (15.25 oz) whole kernel sweet corn, drained
  • 1  can (14.5 oz)  diced tomatoes, drained
  • 1  cup chopped red bell pepper
  • 1/2  cup crumbled goat cheese
  • 2 Tablespoons balsamic vinegar

Rinse quinoa under cold water 1 minute; drain. Cook quinoa as directed on package; drain. Cool completely, about 30 minutes.
Meanwhile, in small nonmetal bowl, place lemon juice, oil and basil; mix well. Set aside for dressing.
In large bowl, gently toss cooked quinoa, beans, corn, tomatoes, bell pepper. Pour dressing and balsamic vinegar over quinoa mixture; toss gently to coat. Serve immediately or refrigerate 1 to 2 hours before serving.
Just before serving, sprinkle with goat cheese. Garnish with basil leaves if desired.




Ways to use Whey

Whey protein is typically known amongst the work out crowds as a lean muscle recovery protein. It works hand in hand with the breakdown of muscle during the work out to rebuild and repair those muscle fibers. However, whey also has its place in a regular healthy diet for similar reasons: it can be a nutritional and complete source of all amino acids, and not necessarily only for athletes.

The most common use for whey is making protein shakes/smoothies however whey can also be incorporated in any overall health plan as quite the versatile ingredient in many simple and fun recipes. In all of these options, it offers a high quality dairy protein boost.

Here is one favourite created by Chris Mohv, owner of Mohv Results, Inc. This interesting way of using whey not only adds variety and interest to a meal, but it also offers 22 grams of protein and 10 grams of fiber.

protein guac

– 3 snack bites of Cabot Light Cheese (50% less fat) or 2.25 oz shredded cheese
– 1 sprouted whole grain tortilla
– ¼ onion, grilled
– 3 slices of fresh tomato

– 1 avocado
– ¼ cup whey protein isolate, unflavored (about 1 scoop)
– 1-2 tbsp chopped fresh cilantro
– Juice of ½ lime
– Pinch of salt

Makes 2 servings


  1. Place the cheese on the whole grain tortilla.
  2. Spray a small pan with nonstick cooking spray and warm over medium heat.  Add the tortilla to the pan, cheese side up.
  3. When the cheese is melted, top with grilled onions and fresh tomato.  Fold the tortilla in half and remove from the pan.  Cut in half.
  1. Slice the avocado in half and remove the pit.  Scoop out the avocado and place in a medium bowl.  Mash until smooth.
  2. Add whey protein isolate, cilantro, and lime juice.  Combine until smooth.  Flavor to taste with salt.
  3. Scoop half of the guacamole onto each quesadilla slice.  Serve immediately.
Substitute grilled onions and tomato with your favorite vegetables.
Ingredient substitutions will change the nutrition information.

Nutrition information for 1 serving (½ of the quesadilla topped with ½ of the guacamole): 368 calories, 22 g protein (including 8 g of whey protein), 26 g carbohydrate, 10 g fiber, 22 g fat, 6 g saturated fat, 291 mg sodium
Also contains: vitamin A, vitamin B6, vitamin C, folate, vitamin K, calcium, copper, potassium

For more information and about whey, visit:


There are many more recipe ideas on this site too!!