Calculating my diets nutritional breakdown

Question
QUESTION: Hi

I've been trying to do a nutritional breakdown of my diet to establish the percentage Protein, Carbohydrate (complex and sugar),and Fat (especially Saturated Fat) I consume.

I've been keeping a detailed food diary and nutritional details of each food I eat including the weight.

After seven days I added the weekly total weight of all my meals from the details on the packaging or raw weight if fresh and divided this by the weekly total weight of each food group (Protein, Carbs., Fat).

By my calculations, which I checked and rechecked, each day I consumed approximately 2600 kcals and 1700 grams of food and calorific drink ( I included my daily intake of one glass of wine in the calculations, but excluded the likes of green tea and water).

What is the most accurate way of extrapolating my weekly % consumption of each food group please?

My previous calculations have fallen short in that when totalled the percentages didnt add up to 100%.

Also assuming my daily intake of protein was 51 grams and my daily consumption of carbs was 313 grams, when divided into my total daily weight consumed (1550 grams) of all food groups consumed this would reveal a daily intake of 30% Protein and only 4% Carbs, which clearly isnt correct.

Any advice much appreciated.

Many thanks

Andrew

ANSWER: Hi Andrew,
I can help you with this!

First of all, you have to be able to check your math and recognize what makes sense: in the example you gave, if you ate 51 grams of protein and 313 grams of carb, clearly the carb should be 6 times the protein percentage, right? Because you ate 6 times as many grams of carb (over 300) as protein (about 50). So however you got the numbers, it's important to recognize when your answers don't make sense so you can start over and re-calculate.

Now, here's how you figure your percentage of carb, protein, and fat. It goes by calories only, so the weight of the foods do not matter at all--total weight, dry weight, none of it is applicable, so toss those figures out. Don't even bother writing them down because having them around will confuse the math!

Take the total calories you eat per day. Let's say you ate 2100 calories and use the above figures of 313 grams carb and 51 grams protein. Protein has 4 calories per gram. So you multiply 4 x 51 and you get 204 calories from protein. Then you divide 204/2100 to get the percentage: 204/2100 x 100 is nearly 10%.
Now for the carbs: There are 4 calories per gram of carbs. 4 x 313 is 1252. then you divide 1252 by 2100 to get the percentage of carbs you ate. 1252/2100 x 100 = about 60%.

I believe when you start doing this you will likely have a higher number of grams of protein you are eating. Remember, only read the "grams of protein" on the food label, and not the weight of anything.

When you calculate fat calories, there is a difference: fat has 9 calories per gram. This will show you that, even when you eat little fat, it quickly becomes a high percentage of your calories because there are more than TWICE the calories in fat than in protein and carbs.

You can play with numbers and check your math on most food labels. Take the figures on a carton of milk, a box of cereal, a bag of chips, etc. You'll find all the information you need, and lots of times they will even have it broken down to what you're looking for.

Please write back if you're having trouble figuring it out the way I explained it and we'll do some more examples :)

Laurie

---------- FOLLOW-UP ----------

QUESTION: Hi Laurie

Thanks for your prompt and helpful response.

I've tried applying the rules you kindly provided but my answers still seem skewed.

For example my average daily calorific intake (calculated by totalling each days calories and dividing my seven) is 2384 calories.

My average daily Carbohydrate intake is 368 Grams. If I multiply this by 4 (calories per gram) I get 1472. If I divide my daily total of 2384 by 1472 = 1.6 % which can't be correct?

Similarly 2384 divided by 347 (daily protein x 4) = approx. 7%.

Lastly Fat- 2384 divided by 453 (daily fat x 9) = approx. 5%.

When added together the percentages total only 13.6%!?

What about Fibre (which is listed seperate from the other nutrients on UK labels. How do I calculate it?

Help please.

Thanks again
Regards
Andrew

Answer
Sure, Andrew!

Remember when you are looking for the percentage, you put the smaller number (portion) on top of the total number. Like if you are trying to calculate how much a quarter is compared to a dollar, you put 25/100 and get, well, 25%, right?!

Your aim is to find out "what portion of the total calories is my carb intake", so you put the portion over the total calories.
So you've been doing them upside down and getting the wrong answer.

Take your carb intake and divide it by the total calorie intake: 368 x 4 = 1472. Then 1472/2384 = 61.7%.
For protein, 347/2384 = 14.5%. and for fat, 453/2384 = 19%.
Add these up (62 + 15 + 19) and you get 96%, which is a whole lot closer to 100 than you've been getting!

Fiber does not have calories, so you can't get a percent of calories from fiber. Sometimes it's counted in with carbs, and some foods elect not to count it as part of the calories because technically your body does not digest it so you don't get calories from it.

Keep trying, and let me know if you get stuck again :)

Laurie

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