Another "effects of..." infographic is making the rounds of Facebook today about the effects of eating a Big Mac. At a cursory glance it seems to mix preposterous claims ("it takes days for you to digest food") with realistic ones ("your brain prefers high-calorie food").

big mac infographic

We have already studied a few of these claims, and I've included the links for completeness. Can we look at the evidence behind the others?

  1. Our brains evolved during a time when food was scarce, so we became adept at choosing high-calorie foods.

Is this true?

  1. Both ingredients [high-fructose corn syrup and sodium] are addictive.

Sugar is not particularly addictive, but what about sodium?

  1. 970 milligrams of sodium trick you into thinking you need to go back for another helping of food.

Is this true?

  1. Ingesting too much sodium causes high blood pressure and can ultimately lead to heart disease and stroke.

The effects of sodium are disputed

  1. Do you ever still feel hungry after just having eaten a Big Mac? This is because you have lost control of your blood sugar, making you crave even more fast food.

Sugar does not make you crave food

  1. The first time you consume a high-calorie meal, your insulin response can reduce your glucose levels making you want to eat more. The high-fructose corn syrup in the Big Mac bun is quickly absorbed by the GI tract, causing insulin spikes and even greater hunger pangs.

Does eating a big mac make you more hungry because of its contents?

  1. Normally the body takes about 24 to 72 hours to digest food. However, hamburgers take a lot more time to digest because they are greasier. It can take more than three days to fully digest a Big Mac.

Are these numbers accurate?

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    I realize the question is broad, and I am prepared to offer a bounty to any particularly comprehensive answer.
    – Sklivvz
    Sep 24, 2015 at 16:11
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    Though I am very interested in seeing an answer to this one, I'm getting really tired of social media and news organizations selling these "what happens after X" infographics with no citations. Some of these things are pretty subjective; how do they define "high levels" of corn syrup? According to McDonald's, a Big Mac has 9 grams of sugar, which I wouldn't call that high given how much sugar is in many other foods. bit.ly/1nmpG8N Sep 24, 2015 at 23:49
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    The part about trans fat taking 51 days to digest seems made up, since I can find no other source making this kind of claim about it. I'm pretty sure that the body also doesn't store fats in their original form, but I am not a medical or nutritional professional. Sep 24, 2015 at 23:54

1 Answer 1


Americans approximately consume about 5 billion hamburgers a year and it is presumed that most hamburgers are composed primarily of meat. However, research by Prayson B et.al. in 2008 shows that:

Meat content in the hamburgers ranged from 2.1% to 14.8% (median, 12.1%). The cost per gram of hamburger ranged from $0.02 to $0.16 (median, $0.03) and did not correlate with meat content.

Recent research by Erica M. Schulte et.al in 2015 shows that not all foods are equally implicated in addictive-like eating behavior, and highly processed foods, which may share characteristics with drugs of abuse (e.g. high dose, rapid rate of absorption) appear to be particularly associated with food addiction.

Our brains evolved during a time when food was scarce, so we became adept at choosing high-calorie foods

The claim is only partially true.

Research shows that human liking for fats may be a consequence of evolutionary pressures to select energy-dense foods to assure nutrition and survival per Drewnowski and Rock in 1995 and this does not include research evidence for brains.

Research also shows that preference for high-fat foods appear to be a universal human trait, and in the absence of efficient physiologic mechanisms regulating fat intake, fat consumption appears to be determined simply by the amount of fat available in the food supply.

Both ingredients [high-fructose corn syrup and sodium] are addictive

The claim is partially true since there is minimal evidence for HFCS addiction and good evidence for sodium craving.

HFCS: High-fructose corn syrup was developed and patented by Japanese researcher Yoshiyuki Takasaki in part during the 1960s and '70s. Studies that have documented fructose's journey through the human body suggest that the liver converts as much as 50 percent of fructose into glucose, around 30 percent of fructose into lactate and less than one percent into fats. In contrast, mice and rats turn more than 50 percent of fructose into fats and sugar addiction, including tolerance and withdrawal, has been demonstrated in rodents but not humans.

According to documented research summaries here, here and here, HFCS addiction does not have sufficient evidence. There is no substantive evidence that high-fructose corn syrup causes excessive weight gain and it probably has no effect on metabolic diseases (Type 2 diabetes), no more than any other sugar or foods.

Sodium: Per Michael J. Morris in 2008, findings from animal studies suggest that changes in sodium status can alter the chemistry and anatomy of putative reward pathways in the brain, the same pathways impacted by drugs of abuse and potentially involved in maintaining addiction.

970 milligrams of sodium trick you into thinking you need to go back for another helping of food

The claim is partially false, based on research evidence below.

The worldwide average salt intake per individual is approximately 10 g/day, which is greater than the FDA recommended intake by about 7.7 g.

A McDonald's Big Mac contains sodium ranging from researched 1010 mg to the advertised 2,425 mg (varies according to the region) which is slightly higher than the FDA recommended intake of 2,300 milligrams of sodium a day (about a teaspoon of table salt). Limited evidence suggests that the high salt content of fast food may increase addictive potential.

Ingesting too much sodium causes high blood pressure, heart disease and stroke

This is partially true.

Both human and animal studies have provided evidence that there may be a strong genetic component underlying the susceptibility to salt-sensitive hypertension. Per research evidence from DASH and TOHP studies, Harvard health states,

reducing dietary salt will lower blood pressure, protecting against heart attack and stroke. Even modest salt restriction improves vascular reactivity and reduces urinary albumin loss, which protects the kidneys and the heart. Salt restriction also lowers the risk of kidney stones by reducing the amount of calcium in the urine.

However per SA, meta-analysis of seven studies in 2011 which involved total of 6,250 subjects in the American Journal of Hypertension found no strong evidence that cutting salt intake reduces the risk for heart attacks, strokes or death in people with normal or high blood pressure.

Loss of control of blood sugar, making you crave even more fast food

This is partially false since this effect is not due to the Big Mac but due to the soda which accompanies most fast food meals which increases the sugar content 10-fold.

According to Garber AK in 2011,

limited evidence suggests that the high fat and salt content of fast food may increase addictive potential. Characteristics of fast food consumers or the presentation and packaging of fast food may encourage substance dependence, as defined by the American Psychiatric Association.

The HFCS in the Big Mac bun is quickly absorbed by the GI tract, causing insulin spikes and even greater hunger pangs

Claim is false.

Per latest research by Stanhope KL in 2015,

Furthermore, recent reports conclude that there are no adverse effects of consuming beverages containing up to 30% Ereq sucrose or HFCS, and the conclusions from several meta-analyses suggest that fructose has no specific adverse effects relative to any other carbohydrate. There is also little data to determine whether the form in which added sugar is consumed, as beverage or as solid food, affects its potential to promote weight gain.

Per research by Salwa W Rizkalla in 2010, a moderate dose (≤ 50g/day) of added fructose had no deleterious effect on fasting and postprandial triglycerides, glucose control and insulin resistance.

Per Tappy and Lê in 2010,

1) There is no unequivocal evidence that fructose intake at moderate doses is directly related with adverse events in man

2) There is no direct evidence for more serious metabolic consequences of high fructose corn syrup versus sucrose consumption.

Hamburgers take more than 24 to 72 hours to digest because they are greasier

This is false.

It might take 1 to 3 days depending on the food per Dian Dooley in 2002. She further states,

if you are talking just about the hamburger meat or if you are talking about a hamburger sandwich with all the trimmings, the answer is about the same. It takes about 24-72 hours for most people's digestive tract to do its job on the food eaten...depends on the person, the food, the person's state of health, medications they might be on, their emotions, etc...but, on the whole 1-3 days will completely digest, or break apart, the food.

  • +1 but maybe change formatting so that the claim is easier to distinguish from the sentence you use it in? Maybe change the claim to bold/italic or so.
    – stijn
    Sep 25, 2015 at 6:21
  • @stijn-Formatting to italics for the claim is done Sep 25, 2015 at 6:27
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    sorry, should have been more clear: my problem is I cannot distinguish easily between the actual claim (like Our brains evolved during a time when food was scarce, so we became adept at choosing high-calorie foods) and your answer to it (like is only partially true since....) because it is put in one grammatically weird/incorrect single sentence. I suggest you make just the claim bold/italic and leave your answer to it bold. That should make it clear what is what.
    – stijn
    Sep 25, 2015 at 6:35
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    @stijn-Formatting for the claim is done per your latest comments. Sep 25, 2015 at 7:13
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    Are you sure you aren't being too selective with the research? One can just as easily find papers saying HFCS does cause insulin resistance etc. Furthermore any quickly digested carbs are going blood sugars to rapidly rise. Your third last point asserts without evidence that this is because of the soda. Sep 27, 2015 at 10:43

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