1 00:00:02,040 --> 00:00:07,080 Speaker 1: Welcome to brain Stuff from how Stuff Works. Hey, brain Stuff, 2 00:00:07,120 --> 00:00:10,520 Speaker 1: Lauren vocal bam. Here. You know that ravenously hungry feeling 3 00:00:10,520 --> 00:00:12,920 Speaker 1: you get after going swimming. It feels like you could 4 00:00:12,960 --> 00:00:14,760 Speaker 1: go to and All you can Eat buffet and make 5 00:00:14,800 --> 00:00:18,320 Speaker 1: them rethink their business strategy. But although a salad or 6 00:00:18,320 --> 00:00:20,959 Speaker 1: a granola bar, or even a nice smoothie would probably 7 00:00:21,000 --> 00:00:24,480 Speaker 1: satisfy you, a voice echoing out of the deepest recesses 8 00:00:24,480 --> 00:00:27,360 Speaker 1: of your brain commands you defeat it something warm, an 9 00:00:27,520 --> 00:00:31,640 Speaker 1: entire pizza, perhaps, or two giant bowls of extra brisket please. 10 00:00:32,680 --> 00:00:35,040 Speaker 1: There could be a lot of reasons why we crave 11 00:00:35,080 --> 00:00:37,960 Speaker 1: warm foods when we're especially hungry, but what of them 12 00:00:37,960 --> 00:00:40,839 Speaker 1: probably has to do with the link between smell and taste. 13 00:00:41,479 --> 00:00:44,440 Speaker 1: We spoke with Dr Stephen Secker, an associate professor in 14 00:00:44,440 --> 00:00:47,920 Speaker 1: the University of Alabama Department of Biological Sciences who studies 15 00:00:47,960 --> 00:00:52,520 Speaker 1: the physiological design of digestive systems. He said, hot food 16 00:00:52,560 --> 00:00:55,960 Speaker 1: emanates much more airborne particles than cold foods, and since 17 00:00:55,960 --> 00:00:58,800 Speaker 1: a large part of our taste sensation also involves smell 18 00:00:59,120 --> 00:01:02,120 Speaker 1: hot food, would they or for provide positive reinforcement in 19 00:01:02,160 --> 00:01:06,119 Speaker 1: its selection? Just consider how quickly the smell of smoke 20 00:01:06,160 --> 00:01:08,679 Speaker 1: from a barbecue can make you feel hungry or how 21 00:01:08,800 --> 00:01:11,560 Speaker 1: no matter how tasty it will be, a cold gaspacho 22 00:01:11,600 --> 00:01:14,800 Speaker 1: simply doesn't stimulate the senses like a warm chili. So 23 00:01:14,880 --> 00:01:17,640 Speaker 1: even though we intellectually know that cold soup is going 24 00:01:17,680 --> 00:01:20,600 Speaker 1: to be good and fill us up, our olfactory apparatus 25 00:01:20,600 --> 00:01:23,240 Speaker 1: hasn't yet been appraised of the situation, making it hard 26 00:01:23,319 --> 00:01:24,840 Speaker 1: to get all the parts of the brain on the 27 00:01:24,880 --> 00:01:29,640 Speaker 1: same gaspacho bandwagon. But smell may not be the only 28 00:01:29,680 --> 00:01:32,000 Speaker 1: reason we crave a hot meal more than a cold one, 29 00:01:32,319 --> 00:01:36,119 Speaker 1: or rather, it may signal a deeper reason. Since heating 30 00:01:36,160 --> 00:01:38,800 Speaker 1: food unlocks calories and nutrients we wouldn't be able to 31 00:01:38,840 --> 00:01:41,520 Speaker 1: get eating the food raw, and since our big brains 32 00:01:41,520 --> 00:01:44,680 Speaker 1: are very calorie meaty, our preference for hot meals might 33 00:01:44,800 --> 00:01:47,319 Speaker 1: have something to do with our brains steering us towards 34 00:01:47,360 --> 00:01:50,600 Speaker 1: the most potential calories possible in the moment of hunger. 35 00:01:51,200 --> 00:01:54,600 Speaker 1: According to Richard Rangum, a biological anthropologist at Harvard and 36 00:01:54,680 --> 00:01:57,760 Speaker 1: author of Catching Fire, How Cooking Made Us Human, the 37 00:01:57,800 --> 00:02:00,960 Speaker 1: important comparison is between foods that are cooked and differ 38 00:02:01,040 --> 00:02:05,040 Speaker 1: only in temperature. He said, hot food very likely yields 39 00:02:05,040 --> 00:02:08,160 Speaker 1: more net energy gain than cold food, partly because of 40 00:02:08,240 --> 00:02:12,600 Speaker 1: changes in digestibility. One example is that starch becomes increasingly 41 00:02:12,600 --> 00:02:15,840 Speaker 1: refractory after hot bread than cools, which could be one 42 00:02:15,880 --> 00:02:18,560 Speaker 1: reason why we like hot toast. In the case of 43 00:02:18,600 --> 00:02:21,079 Speaker 1: lipid rich foods, the closer of fat is to its 44 00:02:21,080 --> 00:02:25,520 Speaker 1: melting point when eaten probably the easier it is digested. However, 45 00:02:25,639 --> 00:02:29,360 Speaker 1: Succor clarifies that chewing and the digestive process are both 46 00:02:29,440 --> 00:02:32,359 Speaker 1: pretty good at unlocking nutrients. He said that once you've 47 00:02:32,400 --> 00:02:35,359 Speaker 1: cooked hamburger, for example, eating it hot or cold would 48 00:02:35,360 --> 00:02:39,600 Speaker 1: provide a negligible difference in calories consumed and digestion effort. 49 00:02:40,480 --> 00:02:43,800 Speaker 1: But there's also the nostalgia factor. Smell is the most 50 00:02:43,840 --> 00:02:47,680 Speaker 1: nostalgia triggering sense. Researchers aren't entirely sure why this is, 51 00:02:47,880 --> 00:02:49,639 Speaker 1: but they think it has to do with the physical 52 00:02:49,639 --> 00:02:52,680 Speaker 1: way our brains handle information in the parts known as 53 00:02:52,760 --> 00:02:56,520 Speaker 1: the limbic system. The limbic system includes the amygdala, which 54 00:02:56,560 --> 00:03:00,840 Speaker 1: helps us process emotions, the hippocampus, which processes and stores memories, 55 00:03:01,080 --> 00:03:04,440 Speaker 1: and the olfactory bulb, which processes scent input from our 56 00:03:04,520 --> 00:03:09,120 Speaker 1: nasal cavity. There are direct connections among these three brain bits. 57 00:03:09,639 --> 00:03:12,400 Speaker 1: Studies have shown that sense create more positive and more 58 00:03:12,440 --> 00:03:16,160 Speaker 1: emotional senses of nostalgia than other triggers, and scientists think 59 00:03:16,240 --> 00:03:19,560 Speaker 1: that's because of these close connections amongst scent, emotion, and 60 00:03:19,639 --> 00:03:23,359 Speaker 1: memory in our brains. While there might be some selected 61 00:03:23,440 --> 00:03:26,160 Speaker 1: drive hidden in our behavior to crave cooked food for 62 00:03:26,240 --> 00:03:29,639 Speaker 1: nutritional gains, are cravings, and our susceptibility to a rich 63 00:03:29,680 --> 00:03:32,000 Speaker 1: scent in the air is very likely driven by a 64 00:03:32,080 --> 00:03:34,680 Speaker 1: nice memory of the taste and smell of food right 65 00:03:34,720 --> 00:03:36,960 Speaker 1: off the grill, or the chicken soup that comforted you 66 00:03:37,000 --> 00:03:40,600 Speaker 1: when you were sick as a child. However, even small 67 00:03:40,680 --> 00:03:43,080 Speaker 1: changes in temperature can make a big difference in how 68 00:03:43,120 --> 00:03:46,560 Speaker 1: satisfaction and food is perceived. It's important to remember that 69 00:03:46,600 --> 00:03:49,280 Speaker 1: the texture of foods, and especially fats like those in 70 00:03:49,360 --> 00:03:53,200 Speaker 1: cheese and cheese substitutes, changes drastically within a relatively small 71 00:03:53,200 --> 00:03:58,680 Speaker 1: temperature range. For example, cold pizza, delight, or horror discuss 72 00:04:00,280 --> 00:04:06,560 Speaker 1: h Today's episode was written by Jesselyn Shields and produced 73 00:04:06,560 --> 00:04:08,680 Speaker 1: by Tyler Clang. For more on this and lots of 74 00:04:08,680 --> 00:04:11,600 Speaker 1: other savory topics, visit our home planet, how Stuff Works 75 00:04:11,640 --> 00:04:23,320 Speaker 1: dot com.