# Breakfast **URL:** \ **Category:** Factual Questions\ **Created:** [August 28, 2014, 8:57pm UTC](https://boards.straightdope.com/t/breakfast/696796 "2014-08-28T20:57:02Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [August 28, 2014, 8:57pm UTC](https://boards.straightdope.com/t/breakfast/696796/1 "2014-08-28T20:57:02Z")
[Why Eating the Right Breakfast Is So Important - Consumer Reports](http://www.consumerreports.org/cro/magazine/2014/10/why-eating-the-right-breakfast-is-so-important/index.htm) That is what I’ve always read, but a local newspaper article and a local news report were contra. They said that it makes no difference. What’s the straight dope? Dr. Mirkin’s newsletter states: > [@](#): > > This month’s issue of The American Journal of Clinical Nutrition contains three studies on breakfast. One study shows that whether you eat breakfast or not doesn’t affect your weight at all (American Journal of Clinical Nutrition, 2014;100:507-13). Three hundred volunteers who were trying to lose weight were told to 1) skip breakfast, 2) always eat breakfast, or 3) continue their current habit regarding breakfast. Sixteen weeks later, none had lost much weight. > > The second study showed that people burn calories at the same rate, and have the same body weight, cholesterol, and blood sugar levels, whether or not they eat breakfast (American Journal of Clinical Nutrition, 2014;100:539-47). Thirty-three people who were not overweight wore machines that determined how many calories they burned throughout the day. After six weeks, the breakfast eaters were more active and burned about 500 more calories during the morning, but they also consumed 500 calories at breakfast, so they neither gained nor lost weight. The breakfast skippers didn’t move around as much in the mornings as the breakfast eaters, but they did not make up for their lost breakfast calories by eating more during the rest of the day. He adds: > [@](#): > > The third study showed that eating breakfast improves a child’s ability to solve problems and do better in school (American Journal of Clinical Nutrition, 2014;100:626-56). This study confirms many previous studies showing that breakfast benefits school children. They have better memory and attention (Appetite, 2012 Dec; 59(3):646-9), they perform better with their school work (Pediatrics, 2008 Aug; 122(2):279-84), they learn faster (Physiol Behav, 2011 Jul 6; 103(5):431-9), and they solve math problems faster and better (Physiol Behav, 2012 Jun 25; 106(4):548-55). I gather from Dr. Mirkin that only schoolchildren are affected by this issue, but that eating breakfast helps you exercise more. As to eating breakfast before exercise: > [@](#): > > It depends on how hard you plan to exercise. When you are going to exercise at low intensity, you don’t need breakfast. However, when you are going to take an intense workout or compete, you are better off eating first. You should eat before you try to exercise intensely for more than an hour. Your brain gets more than 98 percent of its energy from sugar in your bloodstream, but there is only enough sugar in your bloodstream to last three minutes. Your liver must release sugar constantly from its cells into your bloodstream to feed your brain. There is only enough sugar in your liver to last a little more than an hour when you exercise vigorously. When you run out of liver sugar, your blood sugar drops and your brain tells you that you feel tired. You have to take additional sources of sugar during intense exercise lasting more than 70 minutes. ---
**Author:** ![Sherrerd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sherrerd/32/8_2.png) [@Sherrerd](https://boards.straightdope.com/u/Sherrerd)\ **Post date:** [August 28, 2014, 10:05pm UTC](https://boards.straightdope.com/t/breakfast/696796/2 "2014-08-28T22:05:31Z")
The studies don’t seem entirely contradictory to me. The ones that say there’s no difference in weight loss (for people who eat some of their daily calories at breakfast, versus eating all the daily calories later in the day), aren’t measuring work done (brain work or physical exercise) in the post-breakfast hours. The focus of those studies was on the question of weight changes only. The studies that say that eating breakfast does make a difference, seem to be looking at the issue of work (brain and/or non-brain) done in the post-breakfast hours–rather than looking at the question of changes in weight. The verdict there seems to be that having some of one’s daily total of calories during the breakfast hours IS helpful for getting brain work and exercise done. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 29, 2014, 12:00am UTC](https://boards.straightdope.com/t/breakfast/696796/3 "2014-08-29T00:00:35Z")
The Consumer Reports article has a lot of “mights” in there … appropriately so and the recent two small studies mearly reaffirms the need to keep them there. Focus on small and not enough detail reported out. One was under 300 participants and one just 33. _What_ breakfast consisted of was not reported out. Was it whole grain cereal and milk with berries? Or sugar bomb cereal? Or a stack of pancakes with syrup? Or a Greek yogurt with a not over ripe banana? **It likely matters**. It is up aginst observational studies (as reported in your cited article) “more than 100 [observational] studies have linked eating breakfast with a reduced risk of obesity” including ones 27,000 and nearly 30,000 subjects strong. One of the studies found no impact on weight loss. Okay. One study thrown into the pool of data that is suggestive but not conclusive. The other found that breakfast helps decrease inactivity. Those who ate 500 calories at breakfast moved around 500 calories worth more in the next few hours. Calorie-wise a wash but given that inactivity is associated with a host of adverse health outcomes a net plus overall I’d say. Hard data still does not exist to beat people over the head with but my educated best guess is that a _healthy_ breakfast (high fiber, high protein, low glycemic index) is going to be associated with a significant net benefit to skipping, even if weight is unchanged. That said there is a modest body of evidence that demonstrates some benefits to having no food for most of the day (variants of intermittent fasting) which most in practice effect by making a late afternoon or early evening meal a single meal of the day. I’d _suspect_ that they’d be better off having that meal be earlier than later but the bottom line for now is … who knows? ---
**Author:** ![iljitsch](https://avatars.discourse-cdn.com/v4/letter/i/77aa72/32.png) [@iljitsch](https://boards.straightdope.com/u/iljitsch)\ **Post date:** [August 29, 2014, 8:42am UTC](https://boards.straightdope.com/t/breakfast/696796/4 "2014-08-29T08:42:40Z")
> [@barbitu8](#): > > You should eat before you try to exercise intensely for more than an hour. Your brain gets more than 98 percent of its energy from sugar in your bloodstream, but there is only enough sugar in your bloodstream to last three minutes. Your liver must release sugar constantly from its cells into your bloodstream to feed your brain. There is only enough sugar in your liver to last a little more than an hour when you exercise vigorously. When you run out of liver sugar, your blood sugar drops and your brain tells you that you feel tired. You have to take additional sources of sugar during intense exercise lasting more than 70 minutes. I’m pretty sure this is nonsense. The unstated assumption here is that vigorous exercise will deplete your blood glucose so nothing is left for your brain. That’s not how it works. Most cells, including muscle cells, don’t get to use blood glucose unless there’s a sufficient insulin level. If you don’t eat, there’s very little insulin so basically all the glucose released by the liver goes directly to your brain and nowhere else. Not sure if the brain uses more energy when you exercise, but I assume the difference is going to be small. All the while, muscles will have to make do with the glycogen stored in them and the fatty acids they can obtain from blood. Burning fatty acids is less efficient, and I believe it even uses more oxygen for the same amount of energy, so running out of glycogen is the main problem with sustained exercise. The brain can function just fine when fasting, it does that every night, unless you wake up in the middle of the night for a snack. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 29, 2014, 11:58am UTC](https://boards.straightdope.com/t/breakfast/696796/5 "2014-08-29T11:58:07Z")
> [@iljitsch](#): > > I’m pretty sure this is nonsense. > > The unstated assumption here is that vigorous exercise will deplete your blood glucose so nothing is left for your brain. That’s not how it works. Most cells, including muscle cells, don’t get to use blood glucose unless there’s a sufficient insulin level. If you don’t eat, there’s very little insulin so basically all the glucose released by the liver goes directly to your brain and nowhere else. Not sure if the brain uses more energy when you exercise, but I assume the difference is going to be small. > > All the while, muscles will have to make do with the glycogen stored in them and the fatty acids they can obtain from blood. Burning fatty acids is less efficient, and I believe it even uses more oxygen for the same amount of energy, so running out of glycogen is the main problem with sustained exercise. > > The brain can function just fine when fasting, it does that every night, unless you wake up in the middle of the night for a snack. No offense but neither of your versions are all that accurate. Muscles do indeed get to use blood glucose during exercise and there is plenty enough insulin around. To more accurate, muscles are directly fueled by ATP which they produce by the metabolism of intramuscular glycogen, blood glucose and blood fatty acids (relatively a slow trickle of energy). Glucose gets in more during exercise both because more is delivered (increased capillary perfusion) and because more gets put across the mebranes (through mechanisms other than increased insulin). More glucose is produced (as the muscles use up their intracellular glycogen stores and suck the glucose out of the blood) by breaking down liver glycogen. A typical person has enough glycogen on board to handle at least 2 hours of moderate intensity activity (few exercise at an intense level for more than 70 minutes at a time) and a trained individual can have greater stores (and greater ability to use fatty acids along the way). Exercise physiology nuts argue about how to eat when. Some point out that occasionally exercising with low glycogen stores can help train the body to use fatty acids more efficiently. And exercising before breakfast [may have some other beneficial effects](http://well.blogs.nytimes.com/2010/12/15/phys-ed-the-benefits-of-exercising-before-breakfast/) as well. Others point out that longer and more intense levels can be sustained if the muscles are as fully tanked up with glycogen beforehand. Most however agree that you should not too much right before intense exercise, maybe an hour or so before is better. Blood flow diverts from the GI tract during intense and prolonged exercise and too much in there will often cause some GI distress. ---
**Author:** ![Hello\_Again](https://avatars.discourse-cdn.com/v4/letter/h/85e7bf/32.png) [@Hello\_Again](https://boards.straightdope.com/u/Hello_Again)\ **Post date:** [August 29, 2014, 1:16pm UTC](https://boards.straightdope.com/t/breakfast/696796/6 "2014-08-29T13:16:31Z")
> [@DSeid](#): > > It is up aginst observational studies (as reported in your cited article) “more than 100 [observational] studies have linked eating breakfast with a reduced risk of obesity” including ones 27,000 and nearly 30,000 subjects strong. The Consumer Reports article is not very impressive however, a meta-study published in the American Journal of Clinical Nutrition found the evidence supported [no link between breakfast and obesity](http://www.ncbi.nlm.nih.gov/pubmed/24004890). ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 29, 2014, 2:17pm UTC](https://boards.straightdope.com/t/breakfast/696796/7 "2014-08-29T14:17:33Z")
I am familiar with that article and _it does not say what you think it says_. The article does not find no link; it accepts the link as firmly established. The focus of that article was about the language used in reporting science, specifically about the “inappropiate use of causal language” … their beef is that those more than 100 observational studies are just that, observational studies establishing an association. Observational studies can suggest causation but do not conclusively estabish it. The observed association is firmly established: those who skip breakfast tend to be fatter and have poorer outcomes and those who eat breakfast tend to be leaner and have better outcomes. They diss the publication of more studies that add to that as “lacking probative value” as it just further establishes what we already know. They further diss the language used in reporting these studies as implying an established causation. This, they argue, is inappropriate and reflects biased research reporting. Their position is that only randomized controlled trials can firmly establish causation and there are few of them that address this issue. Breakfast eating or skipping might be a proxy for types of foods eaten or other lifestyle or personality characteristics, for example. Hence the importance of and attention paid to these very small and incomplete studies: they are randomized controlled trials. Again one that did not specify what breakfast _was_ found that people randomized to eat breakfast or skip for 16 weeks had no differences in weight at the end. And another, that also found no difference in weight but found that those who ate breakfast moved more (burning off the additional 500 calories they ate at breakfast while not impacted how much else they ate) and had more stable afternoon and evening blood sugar levels. Reported out in the press as “see, eating breakfast won’t make you lose weight!” and ignoring the benefits observed. ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [August 29, 2014, 8:24pm UTC](https://boards.straightdope.com/t/breakfast/696796/8 "2014-08-29T20:24:28Z")
Thanks everyone for your replies, especially DSeid. Exercise physiology has come a long way in recent decades, but still is a science in progress. As noted, the types of breakfast in the studies were not shown. From my personal experience, if I do my usual workout of an hour of running and nearly an hour of weights, I feel fatigued during my weight session, and I know it affects my workout. If I have my usual breakfast of oatmeal (with my add-ons of chia seeds, hemp hearts, frozen fruits, sliced banana, flax powder, and wheat germ)) with soy milk and a little maple syrup I feel much better. That breakfast also causes me to move my bowels within a few minutes after eating, so I do not have that urge while working out. Sometimes I will run with a friend who wants to run at sunrise, so I postpone breakfast then until after the run, and then I will do the weights. I feel fine for the run then. I will note, also anecdotally, that I never eat before a race, and when I was doing marathons, not even before a marathon. In those days these gels and energy packs were not available and all I drank was water and Gatorade if provided. One marathon around 1980 near Chicago provided only water as the conventional wisdom then was sugar would slow down water absorption. We now know (thanks to Dr. Noakes) that glucose in a 6% solution or less will not slow down water absorption. Since Dr. Noakes published his book (_Lore of Running_, I’ve read that it could be up to 10%. Does anyone have the straight dope as to the glucose solution? ---
**Author:** ![iljitsch](https://avatars.discourse-cdn.com/v4/letter/i/77aa72/32.png) [@iljitsch](https://boards.straightdope.com/u/iljitsch)\ **Post date:** [August 29, 2014, 9:34pm UTC](https://boards.straightdope.com/t/breakfast/696796/9 "2014-08-29T21:34:50Z")
Ok, personal experience here: There have been times I ate breakfast, lunch and dinner. Times I only at breakfast and dinner, times I only ate lunch and dinner and even times I only ate dinner. (With a bunch of snacking also, but rarely in the morning.) Throughout those years I gained a large amount of weight. These days, I eat breakfast, lunch, a mid-afternoon mini-meal and dinner and I lost most of my excess weight. For exercise, I cycle, walk and walk up and down stairs. I’m pretty sure I can tell when my glycogen is depleted with the stair walking, which becomes rather difficult when that happens. As I’m on a calorie restricted diet, I reach this stage after 10 - 30 minutes. On my bike or when walking, it’s several hours before I notice I start to slow down a bit but it’s not too bad. I certainly don’t do my best thinking when exercising (research shows that moving your body takes a lot of brain power and impairs higher functions to some degree), but I don’t think my brain suffers from lack of energy at any time, even when the rest of my body does. My advice regarding breakfast: if you don’t eat breakfast and you’re happy with your weight and how your body functions: good for you. But if you don’t eat breakfast and you’re trying to lose weight and/or find yourself scarfing down terrible food later in the day and/or suffer from a lack of energy at some point in the day, maybe it’s time to heed the correlation between maintaining a healthy weight and eating breakfast, and try eating breakfast yourself. If eating first thing in the morning is unpalatable, eating an hour or two later still counts as breakfast, so try that. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 30, 2014, 10:52pm UTC](https://boards.straightdope.com/t/breakfast/696796/10 "2014-08-30T22:52:12Z")
> [@barbitu8](#): > > … Does anyone have the straight dope as to the glucose solution? I don’t. You may want to PM some of the running experts here as they often pay great attention to the latest on that stuff. [This page](http://runnersconnect.net/running-nutrition-articles/best-sports-drink-marathon/) seems to have a pretty reasonable discussion though. They discuss 1 gram/minuge is possible with glucose only drinks and 1.5 gram/minute with 2:1 glucose fructose combinations. They list some beverages that are 8% carb. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [August 31, 2014, 5:18am UTC](https://boards.straightdope.com/t/breakfast/696796/11 "2014-08-31T05:18:14Z")
FWIW I’ve tried to do a small literature skim and the bottom line seems to be that up to 8.6% is possible and best in a 2:1 glucose to fructose ratio. Beyond that they state GI issues become more frequent. [That 2:1 glucose/fructose combination](http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0838.2008.00862.x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false) does seem to result in faster gastric emptying and improved delivery of both carbs and water than just water alone or all glucose in the same concentration. For the wonk wannabe [this](http://www.tandfonline.com/doi/full/10.1080/02640414.2011.585473) seems to be a pretty exhaustive review. Pretty much the same bottom-lines with some neat little additions: First the same information in a bit more detail: > [@](#): > > Surveys of competitive to elite athletes have noted high (∼90 g · h−1) intakes of carbohydrate during exercise (Kimber, Ross, Mason, & Speedy, 2002; Saris, Van Erp-Baart, Brouns, Westerterp, & ten Hoor, 1989). These have been reported during endurance cycling events (Tour de France, Ironman triathlon) in which a relative ease of consuming foods and fluids while exercising combines with extreme fuel requirements, and where energy support may be an additional nutritional goal. Nevertheless, these observations have led to questions of whether it is the guidelines (30–60 g · h−1) or athlete practices that are wrong. … The various interests of gastrointestinal comfort, opportunity to consume carbohydrate while exercising, and the high rates of exogenous carbohydrate oxidation required to maintain power output when glycogen becomes depleted, converge at a carbohydrate ingestion rate of ∼80–90 g · h−1, at least when glucose and fructose are co-ingested in a 2:1 ratio (Jeukendrup, 2010). … studies using multiple transportable carbohydrates have shown benefits to the performance of exercise activities of ∼3 h duration compared with the ingestion of glucose alone (Currell & Jeukendrup, 2008; Triplett, Doyle, Rupp, & Benardot, 2010). Therefore, new guidelines to promote individual experimentation with carbohydrate intakes of up to 90 g · h−1 in ultra-endurance sports are warranted (see Table II). We have provided these guidelines in absolute amounts, based on the evidence that there is little difference in the oxidation of exogenous carbohydrate according to body size/body mass (see Figure 2). Instead, factors such as the carbohydrate content of the habitual diet or intake during training sessions (Cox et al., 2010) may play a role in determining capacity for oxidizing carbohydrate ingested during exercise. … For events (or training sessions) under an hour there is no real _metabolic_ impact from ingesting additional carbs BUT there do seem to be centrally mediated impacts: these can be acieved even by quick mouth rinses with no carbs ingested at all - > [@](#): > > Findings of a lack of improvement of a 1-h cycling protocol with glucose infusion (Carter, Jeukendrup, Mann, & Jones, 2004b) but benefits from carbohydrate ingestion (Carter, Jeukendrup, & Jones, 2004a) created an intriguing hypothesis that the central nervous system might sense the presence of carbohydrate via receptors in the mouth and oral space, promoting an enhanced sense of well-being and improved pacing. This theory was subsequently confirmed by observations that simply rinsing the mouth with a carbohydrate solution can also enhance performance of the cycling bout (Carter et al., 2004a). A number of studies have now investigated this phenomenon, including several in which functional magnetic resonance imaging technology has tracked changes in various areas of the brain with carbohydrate mouth sensing (Chambers, Bridge, & Jones, 2009). In these studies, both sweet and non-sweet carbohydrates were shown to activate regions in the brain associated with reward and motor control. > There is now robust evidence that in situations when a high power output is required over durations of about 45–75 min, mouth rinsing or intake of very small amounts of carbohydrate play a largely non-metabolic role involving the central nervous system in enhancing performance by 2–3% Finally the issue of potential benefits of training low at least some of the time in order to force adaptations tha utilize fatty acids more efficiently … > [@](#): > > Based on convincing evidence of enhanced muscle markers of cellular signalling and metabolic adaptation following training in a low carbohydrate environment, a new concept of dietary periodization has been promoted whereby the athlete should “train low” to promote a greater training response, before switching to high carbohydrate availability for competition when optimal performance is required (Baar & McGee, 2008). … Although training on a high-fat diet is associated with an increased ability to oxidize fat during exercise and a decreased reliance on muscle glycogen utilization (Helge, Watt, Richter, Rennie, & Kiens, 2001; Burke et al., 2002), there are also indications that it can reduce the chronic adaptations to training (Helge, Richter, & Kiens, 1996) and impair carbohydrate utilization (Stellingwerff et al., 2006) and the ability to sustain high-intensity exercise performance (Havemann et al., 2006). Therefore, the more recent train low protocols have utilized a different approach to reducing carbohydrate availability for training. In fact, the protocol used in the primary study used the placement of training sessions rather than dietary manipulation to achieve low glycogen levels for specific workouts. Other ways to selectively reduce carbohydrate availability for training include exercising after an overnight fast, consuming water during prolonged workouts, withholding carbohydrate in the hours after exercise, and restricting carbohydrate below the fuel requirements of the training load (Burke, 2010a). Such protocols differ in the duration of exposure to a low carbohydrate environment as well as the focus on reducing endogenous and/or exogenous carbohydrate stores. … However, changes in muscle physiology are not, per se, a proxy for performance and currently there is no convincing evidence that train low strategies achieve an enhancement of performance over a conventional diet/training approach (Hawley & Burke, 2010). Furthermore, several disadvantages are associated with train low techniques, including an impairment of the ability to train at high intensities; this is not insignificant because it is a cornerstone of the principles of preparation for elite sport. … Important for those of us who just exercise for fitness or recereationally or as week-end warriors? Probably not. And afterall, as those authors point out: > [@](#): > > … athletes already periodize the carbohydrate availability for their training sessions. By design or by accident, some workouts are undertaken with reduced carbohydrate availability … ---
**Author:** ![barbitu8](https://avatars.discourse-cdn.com/v4/letter/b/839c29/32.png) [@barbitu8](https://boards.straightdope.com/u/barbitu8)\ **Post date:** [August 31, 2014, 7:22pm UTC](https://boards.straightdope.com/t/breakfast/696796/12 "2014-08-31T19:22:37Z")
Thanks DSeid for your exhaustive information. Really appreciated.