I lucked out as a kid: my mother was infatuated with nutrition and nutrition labeling and grocery trips often involved us reading labels together. Reading a nutrition label is one of those skills I learned at her feet – like cross-stitch or baking cookies.

So I forget that for a lot of people, nutrition labels can be like hieroglyphs. In the US, there’s been a trend toward advertising some nutrition facts prominently on the front of packages, too (20 grams whole grains per serving! 3 grams fiber per serving!) and these facts, in and of themselves, are essentially worthless when it comes to evaluating whether the food you’re looking at is actually healthy.

In the US, the Nutrition Label begins by designating what a serving size is (usually with a weight measurement in grams as well as either a volumetric measurement (1 Tablespoon) or a counted measurement (about 10 chips).  This section will also list how many servings are in one package.

Then the label will break down how much fat, cholesterol, sodium, carbohydrate and protein are contained in a serving (by gram or milligram), as well as the percentage that figure represents of the USDA Recommended Daily Allowance (for an adult with a 2,000 calorie a day diet).  I have nearly always ignored the percentages on the nutrition label because never, ever in my adult life have I followed a 2,000 calorie a day diet.

Calories:
A calorie is simply a measurement of energy. One gram of Protein or Carbohydrate is four calories. One gram of Fat is nine calories. We refer to protein, carbohydrate and fat as macro-nutrients (“macros”). The calories in a serving of food are the sum of the calories present in the Fat, Carbohydrate and Protein in a serving of food. US nutrition labels also include a line below calories which lists the number of Calories from Fat (if there is any fat in the food). This is because the government believes Americans are too dumb to look at the total fat grams in a serving and multiply by nine – but you can do that just as easily.

Fat:
As stated above, fat is a macronutrient and one gram of fat is 9 calories – making fat the most dense source of calories (or energy) in our food. US nutrition labels are also required to break out the amount of Fat which is Saturated Fat and Trans Fat (if the food contains either of these fats).  It is widely believed by the medical establishment that both Saturated Fat and Trans Fat are unhealthy. However, while the most recent medical research supports the fact that Trans Fat is universally bad for your health, more recent studies refute the earlier findings about Saturated Fat being unhealthy or leading to cardiovascular disease. Occasionally, a nutrition label will also break out the total mono-unsaturated and poly-unsaturated fats included in a serving. So, what’s the difference between saturated, mono-unsaturated and poly-unsaturated fat? It has to do with the chemical structure of the fatty acids (this is when we start talking about Omega 3 or 6 or 9) – which is all a bit above Nutrition Label 101.

Cholesterol:
Cholesterol is contained in your food but also produced by your body – it’s an important molecule that serves many complicated functions in the body, many of which are way above my biological training. Numerous studies have demonstrated a correlation between high cholesterol and artherosclerosis (hardening of the arteries with plaque).

Sodium:
Sodium (and some labels may also break out Potassium) are electrolytes which are necessary for life.  It’s unfortunate that potassium is not required to be listed on US nutrition labels since most people in the US don’t get enough potassium (and don’t believe the hype –the best source is NOT in a banana: try dark leafy greens or avocado).

Total Carbs:
In the US, our nutrition labels are required to list total carbohydrates present, even if those carbohydrates cannot be used for energy (ie, fibers). The US does require labels to list the Fiber and the Sugar included in the Total Carbohydrate count. If you’re diabetic or on a ketogenic diet, people talk about “Net Carbohydrate.” Net carbohydrate is a count of the carbohydrate energy which will impact your blood sugar. Generally speaking, net carbohydrate is simply Total Carb minus Fiber. However, some products may also break out sugar alcohols. Be cautious about sugar alcohols – some of them are more digestible than others and will still result in a spike in blood sugar and an insulin response. Some diet foods *cough*Atkins*cough* will subtract all sugar alcohols from their carbohydrate count even if those sugar alcohols (like maltitol syrup) should be counted.

Protein:
Proteins are molecules made up of amino acids. Humans can synthesize some amino acids, but other amino acids need to be consumed in our food. Vegans and vegetarians will talk about “complete protein” and bodybuilders will talk about “ideal protein”. Both of those concepts have to do with intaking protein which contains all the amino acids humans need in the right ratios.  So even though the nutrition label will give a flat figure for protein – that protein may be incomplete (may not include all the amino acids humans need).  If you eat meat or especially eggs (which have all the necessary amino acids in the right ratio), you likely don’t need to worry about that.

Nutrition Labels also list the percentage of the Recommended Daily Allowance (again, remember this percentage is based on a 2,000 calorie a day diet) of Vitamin A, Vitamin C, Iron and Calcium which are included in a serving of the food.

So now you know how to read a nutrition label – what can you do with that knowledge?

I log all my food intake on Lose It although most people on a ketogenic diet use My Fitness Pal because you can adjust your goals to reflect limiting carbohydrate intake (I don’t use My Fitness Pal because I can’t stand their user interface; their interface for creating recipes was irritating and their food data was often wildly inaccurate). Both Loseit.com and MyFitnessPal.com are free to use and have free downloadable apps for Android; iOS and Windows phones. Whether I’m actively watching what I eat or not, I still log my food every day because I am obsessed with data.

I use nutrition labels and my food logs to help guide my choices for the day.  I have guidelines with regard to the macros (remember – fat, net carbohydrate, protein) I take in daily. I used this site to calculate what my macros should be (ie, how many grams of fat, net carbohydrate and protein I should get in a day) based on my current lean mass and the net carbohydrate goal recommended by my physician of 40 grams.  These macros guide how I look at nutrition labels and how I determine what to eat in a day. Many people on ketogenic diets choose not to log their food and instead stick to their macros by simply reading nutrition labels and still find great success – so if logging seems like an unnecessary pain, reading nutrition labels can assist you in sticking to your macros and meeting your dietary goals.

That being said, I find nutrition labels pretty useless beyond macro-nutrients and base many of my meal decisions on knowing the foods I eat (for example: bell peppers are super high in Vitamin C; pumpkin seeds are high in Magnesium; dark leafy greens are high in Potassium and Iron, although this iron is not as easily absorbed by the body as the iron in a steak. This is knowledge I have accumulated over years of  trying to plan the ideal vegetarian diet, knowledge which is still just as handy when I’m tasked with carving out a healthy and varied approach to a ketogenic diet. But you don’t have to be geeky or encyclopedic about food – the great thing about a keto diet is that if you meet the macro guidelines you set for yourself, chances are you’ll be successful. Sometimes I have to remind myself that good enough is really good enough: everything in life doesn’t have to be optimized.