You do a lot of sit ups and ab work but just not seeing the definition in your abs. We are going to be crunching numbers and talking about everyone's varieties, as average or normal, so do allow a little variation for your body type. If you're short on time to figure out the numbers with me, then go to the end where I have surmised the answer for you.
You'r doing an Australian outhouse load of sit ups. Sit ups give you chiselled abs right? You don't want to look like Arnold Schwarzenegger in his prime you just want abs. I'm sorry to say it doesn't work like that...well actually it does....just not as effectively as you think.
Here come the numbers. I have tried to reference my material wherever possible to prove this is not just conjecture. None of the numbers will fit everybody as everybody's genes and physiology are slightly different so will react in varying degrees of magnitude.
When you oxidise fat, or burn as it’s commonly known, it doesn't usually all come off the area that is being exercised. The fat dissipates evenly(ish) inside and around your body. For your hard work to be visible you need to have minimal fat so that your muscle definition can catch the light, form shadows and make that washboard prominent. You may have heard the quote or similar before "Abs are built in the gym but shown in the kitchen". So we need to fat aka weight. In its simplest form losing weight means burning calories (I said simplest).
How many calories does a single sit up use? There are a lot of factors to consider, such as age, weight, sex and intensity. A sit up is a body weight exercise. That means it falls into a callisthenics category. According to a table published by Harvard Medical School a 115 lb adult will burn 167 calories in a 30 min moderate intensity callisthenics workout. Forgive the assumptions and generalisations, you'd never reach the end of this blog if we broke it down for every body type, age, intensity and sex there ever was. Rounded up, using the information in the table, that's 6 calories a minute. How many sit ups can you do in a minute? When I was at 155 lb or 70 kg I could manage 45 sit ups in a 1 minute fitness test. I was going balls to the wall so I wouldn't say it was moderate. Hows about 30, that's 1 sit up every 2 seconds. 6 calories divided by the 30 sit ups gives us only 0.2 calories per sit up.
...30 sit ups gives us only 0.2 calories per sit up.
Wishnofsky cited by Butler claims 1lb of human fat is around 3500 calories. The caveat here is that this is old research and human fat is not pure fat. Palsdottir says body fat is 87% pure fat. Did you put your calculator away? Using these figures 1 lb of human fat is a touch over 3000 calories. Lets say it's 3000 for the sake of optimism and nice figures.
We know how many calories a single sit up burns (0.2 cal). We know how many calories 1 lb of fat is worth (3000 cal). Plug in the numbers we get 3000 / 0.2 = 15 000. What the faecal biscuit! I knew the figure would be high but 15 000 is not going to be achievable in a short period of time. It's 500 sit ups a day over 30 days. 500 a day is in the realm of possibility but not all day every day. Although, there are other factors that help, we will get onto those.
Let's add some more complications. You're training like Heracles to get the midriff of a Greek God(dess) doing your 500 sit ups a day without fail. Your body fat is going up in flames. Body fat is usually expressed as a percentage of the human body (BF%). The body fat percentage can vary quite a bit with age, gender, diet and genetics. Looking at the average BF%; Women are 27% and Men 18% as found on table 13.1 of Jeukendrup & Gleeson. As you lose weight, providing you don't lose too much muscle and other vital fluids, your body fat percentage will decrease.
What does this % number mean for you? As your body fat % decreases your abs become more likely to be visible. You can't or shouldn't aim for 0%. Your body needs an essential amount of fat to operate. If you aim for zero you'll have bigger worries than if your abs are visible, namely what the hospital menu is. Sara Lindenburg's article reviewed by Daniel Bubnis, MS, NASM-CPT, NASE Level II-CSS, goes on to cover that abs on males and females become visible from 15-19% body fat. If you're an average male you should be seeing glimpses of bumps where you want them. Sorry ladies, you'll have a bit of work to do (on average) but those lines are worth so much more because of it.
With me still? Good. This is where averages become ideals. The ideal weight varies a lot with gender and height. So I've plucked heights form a chart provided by Banner Health. Males at 5 ft 11" should be 155 - 189 lbs and Females at 5 ft 4" between 108 -132 lbs. Lets take the figures in the middle. We have a 172 lb male and a 120 lb female. Taking our average body fat % from earlier that means a male has 31 lbs of fat and a female has 32 lbs. Now the percentages change as weight is lost. We will assume both men and women need to get to 17 % body fat to get some noticeable abs. Looks like men need to only get 2 lbs shifted while the ladies have 6 times that at 12 lbs.
That's a lot of sit ups to do. Ladies, if you wanted abs, through sit ups alone you're going to have to do 180,000 (on average). Gents can chuckle at a measly 30,000. Looking back on my earlier statement, you could get your abs through sit ups alone. I did say other factors come into play. Your resting metabolism burns calories each time you blink, breath, digest food or beat your precious blood pumper. On top of that your ab muscles would be screaming for a healing which burns some calories when you find a moment to not be doing 30,000 - 180,000 sit ups. Plus bigger muscles require more calories for maintenance at rest eating up a few more calories. Again, again, again, this is influenced a lot by your genetic material, workout intensities, age, height, weight, existing body fat %, diet, daily activity, sleep and general health.
Can you get abs through sit ups alone. The short answer is yes. The long answer is above. The middle answer is, it's possible but not probable. We are talking 500 sit ups a day every day not including battling last nights curry. There are other factors that make life simpler, that you can influence, like your diet and activity levels. How much those activities help is a whole'nother blog(s). To all but spell it out; you need to do more than just sit ups. You need to do other resistance work, cardio or activity whereby your heart rate becomes elevated. Healthy diet choices learned from Nutrition Coaching makes the process easier and more efficient. Steady calorie deficits, but not huge, will get you closer to a stomach beaten of metal for a gladiator. Be aware that your genetics may mean your abs are not perfectly symmetrical (I have asymmetrical abs) or just not as prominent. 2, 4, 6 or even 8 packs are not impossible but they certainly don't come easy. Sorry ladies, you can bitch slap mother nature later, you have more crunches to do than the gents. It's up to you to decide on your aesthetics. Don't judge yourself by another, their lifestyle, cash flow, opportunities and genetics will play a huge factor. Your body is yours, you decide what influence you want it to make.
Banner Health (unknown)
Ideal Weight Chart [Online] https://www.bannerhealth.com/staying-well/health-and-wellness/fitness-nutrition/ideal-weight [Accessed 02 Sep 19]
Harvard Medical School (2004) Calories burned in 30 minutes for people of three different weights [Online] https://www.health.harvard.edu/diet-and-weight-loss/calories-burned-in-30-minutes-of-leisure-and-routine-activities [Accessed 29 Aug 19]
Jeukendrup, A & Gleeson, M (unknown) cited by Human Kinectics (unknown)
NORMAL RANGES OF BODY WEIGHT AND BODY FAT [Online] https://uk.humankinetics.com/blogs/excerpts/normal-ranges-of-body-weight-and-body-fat [Accessed 02 Sep 19]
Lindenburg, S (2018) Body Fat Percentage for Abs: What’s the Magic Number? [Online] https://www.healthline.com/health/body-fat-percentage-for-abs [Accessed 02 Sep 19]
Palsdottir, H. (2017) How Many Calories Are in a Pound of Body Fat? [Online] https://www.healthline.com/nutrition/calories-in-a-pound-of-fat [Accessed 29 Aug 2019]
Wishnofsky, M cited in Butler, N.(2019) What to know about calories and body fat https://www.medicalnewstoday.com/articles/325176.php [Accessed 29 Aug 19]