Bite Back with Abbey Sharp - Want to BOOST Your Metabolism? The Science on Metabolism Hacks for Weight Loss

Starting point is 00:00:00 If you were to eat 3 jalapeno peppers to provide 3 mg of capsaicin, you would see a 20% boost in metabolism over a 30 minute period, which again might get you a measly 4.5 extra calories. There are literally more calories in the peppers you ate to burn those calories. Welcome to another episode of Bite Back with Abbey Sharp, where I dismantle diet culture rules, call it the charlatans spinning the pseudoscience and help you achieve food freedom for good. Today I'm gonna be rocking it solo folks I'm going to be unpacking one of the biggest sources of nutrition mysticism ever.

Starting point is 00:00:50 Metabolism. I don't know if this is like a millennial thing, but I feel like most of my earliest diet culture memories centered around the enigma that is metabolism. So like at 13, I had no clue what metabolism actually was. I just knew that adults were worried about it slowing down and then like causing them to instantly gain weight. But those messages were then reinforced by countless magazine headlines touting

Starting point is 00:01:21 the metabolism boosting benefits of like multi mini-meal diets and shady fat burning supplements endorsed by D-list celebs. And taken together all of that resulted in a crushing fear of turning 30 when apparently everything in my body would like suddenly shut down. Well I am 37 years old now and I'm also a nutrition professional who's done her homework, and I'm here to tell you that it's going to be alright. On today's episode, I'm going to be diving into all of your burning metabolism questions.

Starting point is 00:01:58 Can you rev up a slow metabolism with certain foods, supplements, or activities? And how much will that actually move the needle on the scale? A big thank you to my colleague Eric Williamson for his research support on this episode. If you are looking for one-on-one nutrition counseling, I'm going to be leaving a link to his website below. I also want to flag that this episode does discuss calories and metabolism in the context of purposeful weight loss, so if this is not supportive to you, I totally respect that and you can just skip over this episode and I'll catch you at the next one.

Starting point is 00:02:35 Also my general disclaimer that this information is for educational and entertainment purposes only, so it's not a replacement for personalized care, and it's also not a suggestion that anybody needs to lose weight. Finally, don't forget to hit that follow button, leave me a review, and share Byte Back with a friend if you can, because it really, really does help more people gain access to legit science and evidence over sensationalized BS. Alright friends, let's dive in. So I want to start by clarifying what metabolism actually is.

Starting point is 00:03:16 Because most of us simply think of metabolism as like how many calories you can eat in your twenties versus today without gaining weight. And yes, that is part of it. But holistically, it's actually about how well your body accesses nutrients to support all of our body processes as evidenced by good digestion and bowel movements, stable energy and blood sugar levels, and good reproductive health. Just to name a few. So if you imagine all your vital organs as having a job to do, and that all of those

Starting point is 00:03:52 jobs cost energy, metabolism is the compilation of all of those energy or calorie expenses contributing to your daily caloric expenditure. Now often when we talk about our metabolism slowing down, we're talking about it in the context of getting older. At least that's what I heard as like a misguided teen, terrified that I'd wake up 20 pounds heavier on my 25th birthday. But according to research, our metabolism is the fastest it is ever going to be at age one, where babies burn calories 50 times faster

Starting point is 00:04:26 than we do as adults. So yeah, suddenly all that cluster feeding through the night makes a lot more sense. Our metabolism then gradually declines about 3% each year until we're about 20. And then interestingly, from age 20 all the way to 60, our metabolic rate actually remains relatively stable. And then it starts to decline again by less than 1% per year. So no, your metabolism isn't broken when you hit 30 or 40. If you are gaining weight during these phases of life, which to be clear is completely normal and

Starting point is 00:05:06 incredibly common. It has less to do with your metabolism like bottoming out and more to do with the fact that your life priorities have just likely changed from a time when you were single, childless and had little to no responsibilities vying for your self-care time. I mean, when I was 20, I used to have the me time to do a boot camp followed by a yoga class on the weekend if I wanted to. But today it often feels like a struggle just to like get in a walk. But let's just say that for whatever reason, you have put on some weight throughout the years and you want to try to lose it by quote quote boosting your metabolism. You might be tempted by all of the so-called

Starting point is 00:05:50 metabolism boosting hacks that you read about online. So let's walk through some of the most popular suggestions for our hypothetical 150 pound female named Sally. Hack one, eat breakfast. female named Sally. Hack one, eat breakfast. When I was growing up, it was drilled into my brain that if you were to skip breakfast, your metabolism would just like grind to a halt. I would envision my body just building fat cells until I opened my eyes and immediately ate a bite of toast.

Starting point is 00:06:21 Funny how these quote unquote nutrition truths tend to change. The fact is, research has found no major differences in the resting metabolic rates of folks who eat breakfast and those who skip it. Though, if we're getting technical, if skipping breakfast results in a calorie deficit as we often see with like intermittent fasting and that deficit results in weight loss, then yes, there will naturally be a small decrease in your resting metabolism. But otherwise, skipping breakfast won't put out your calorie burning flame. Hack 2.

Starting point is 00:06:57 Eat frequent mini meals and multiple snacks. Millennials like myself grew up being told that we basically had to put something in our mouths like every hour on the hour in order to quote-quote fuel the fire, aka keep our metabolism burning all day. If we were to go too long between meals, again, our body would apparently just start storing fat. Now ironically, the tables have turned and we see people making similar claims about intermittent fasting boosting metabolism. But if we look at

Starting point is 00:07:30 the research we can see that how often you eat throughout the day has little to no influence on 24-hour resting metabolic rate. So eat in a way that fuels you best. For some, that might mean like three big meals a day, and for others, it might mean like six or eight smaller meals. But moving on to more specific metabolic hacks, let's talk about cold plunges. Thanks to the popularity of biohacking and longevity protocols, cold plunging or sitting in icy water for a short period of time has become a super trendy wellness practice. Personally, it sounds like absolute torture and not something I'd be keen on, even if there are some known benefits for like inflammation and exercise recovery.

Starting point is 00:08:22 But cold plunging is also often touted as a metabolism booster by activating something called brown adipose tissue, which has been shown to generate heat and therefore burn more calories at rest. But alas, by how much? Well, when we look at the research, it says that you can boost your metabolism by 47%. And if you're thinking, ah, holy shit, let me go have a cold shower and like the fat will melt away, not so fast. If you're in a cold plunge or a shower for 10 minutes, which in my opinion is a fucking long time to be cold, the effect

Starting point is 00:09:08 will last for only 10 minutes. That would net out at around a 2% increase in metabolism or 4.5 calories burned per day for our girl Sally. That is like the equivalent of a strawberry. And I can promise you a single strawberry never made anyone gain weight. So personally, this would get a pass from me. At least when it comes to metabolism boosting. But if icy cold temperatures doesn't really move the needle, maybe hot will. This is where the common hack to eat lots of spicy food comes into play. Spicy foods like hot peppers are rich in a compound called capsaicin,

Starting point is 00:09:55 which increases epinephrine and heat production in that brown fat tissue that I mentioned a moment ago. According to the results of one systematic review and meta-analysis, capsaicin did offer a slight boost in resting metabolic rate and energy expenditure, but a previous meta-analysis declared that any apparent benefits on paper would be clinically insignificant in the real world.

Starting point is 00:10:22 Don't believe me? Let's do some math. If you were to eat three jalapeno peppers to provide three milligrams of capsaicin, you would see a 20% boost in metabolism over a 30 minute period. Which again, might get you a measly like 4.5 extra calories. There are literally more calories in the peppers that you ate to burn those calories. And I mean, I love spicy food, but the math is just not math-ing. But speaking of things I love, let's talk about our next hack, caffeine, coffee, and green tea extract. If you were to analyze most of the commercial metabolism booster supplements out there,

Starting point is 00:11:10 you'll notice that they usually contain some amount of caffeine. And this makes sense since caffeine has been shown to increase energy expenditure by increasing heat production aka thermogenesis. But again, how much are we talking? Well, what we see is about a 7% increase in metabolic rate over three hours, which then drops in half after five hours and is completely non-existent by the 10 hour mark.

Starting point is 00:11:41 So that gives us around a 3% boost over 10 hours or around 14 calories burned for Sally per day. Green tea extract is also specifically of interest in the supplement world thanks to the unique compound EGCG. And while EGCG does have a lot of unique benefits, the vast majority of studies on metabolism show no increase in energy expenditure and those that do have some positive outcomes only report a 2% to 4% boost in metabolism over 24 hours after taking the supplements several times a day. So if Sally were to drink like highly concentrated green tea like three times a day, she might get a boost of around 10 to 20 calories. Really nothing much to

Starting point is 00:12:34 write home about in my opinion, and those quote-unquote burned calories are very easily cancelled out if you put any milk or cream or sugar in your coffee or tea. I also worry that when people read about caffeine boosting their metabolism, that they automatically think more is better. So while you may be burning an extra 20 calories from continuous cups of coffee, you may also interrupt your sleep, which ultimately makes weight loss a lot harder. So drink your morning coffee or tea for pleasure, joy or in my case survival but not to burn calories or lose weight. Finally let's talk about exercise, specifically high intensity interval training or HIIT workouts.

Starting point is 00:13:25 Specifically, high-intensity interval training or HIIT workouts. Proponents of HIIT training point to what is often known as the afterburn effect, or a temporary boost in calorie expenditure after working out. And yes, when compared to aerobic endurance exercise, HIIT workouts do provide a greater boost in post-exercise energy expenditure. But how much are we actually talking about? Well, this one might actually shock you. We're generally only getting a modest 10% boost that lasts a pathetic 45-60 minutes. So yeah, that's basically just a couple

Starting point is 00:14:06 Cheerios worth of extra calories burned for Sally. That doesn't mean you shouldn't do HIIT training, but in terms of its effects on metabolism, it's kind of a bust. But let's just say our girl Sally had not listened to this episode that you're listening to right now and she went like 100% all in. She did ALL the things to try to transform her metabolism into its former 17 year old self. Hit workouts, cold plunges, ghost peppers galore, coffee and green tea extract, the whole kit and caboodle. Guess how much extra she could potentially burn in a day? 50 calories.

Starting point is 00:14:48 Personally, I can't imagine letting the calorie equivalent of like a kiwi or a clementine completely run my life. But perhaps you hear 50 calories burned and you're like, sweet, sign me up. Uh, not to be a Debbie Downer, but I have another shitty fact to share. There are powerful metabolism boosting supplements that have been shown to help you burn an extra 150 calories per day. And there are medications that make you pee out up to 300 calories. And despite working effectively on the calorie expenditure side of the energy balance equation, the evidence suggests that they don't actually result in fat loss. I know. There are multiple reasons for this, but it's largely related to a strongly regulated feedback

Starting point is 00:15:45 control system between calorie expenditure, or how many calories you're burning, and calorie intake, aka appetite. The more calories you quote-unquote lose, the more you want to eat to make up for them. So while we're all over here obsessing over the metabolism piece of weight management, it's actually far less important than focusing on the appetite management piece that is best achieved through balanced eating. There is however, some ways to support a healthy metabolism in a much more meaningful way than all of those tedious hacks. And for that, I want to bring it back to basics.

Starting point is 00:16:40 Remember, we have all of these organs doing quote-unquote work all the time behind the scenes, and that work costs calories. So we want to do everything we can not to let our organs slack off and do less work. So the first recommendation is to maintain a balanced or very modest plus or minus energy equation. When I say energy equation, I am talking very simply about calorie intake minus calorie expenditure. And among the many reasons why I am vehemently against crash diets is that they can negatively affect our metabolism.

Starting point is 00:17:22 We saw this clearly under the very extreme conditions like those in the Biggest Loser study where, based on their loss of fat mass and lean mass, their metabolism would have been predicted to slow down by about 305 calories per day. But instead, it slowed by twice that amount, 610 calories. And this explains why a third of contestants regained almost all of their weight lost, landing them within 1% of their starting weight. That is not what we want here, folks. Especially after being screamed at for weeks by Jillian Michaels.

Starting point is 00:18:01 Are you ready to work? If you quit on me again, you go home. by Jillian Michaels. Basically, what's happening is that when you're expending a ton of calories doing hours of intense exercise and not eating enough, your thyroid steps in and says, uh, wait a minute here, folks, the tank is getting low. So we better downregulate a lot of our normal healthy functions. If you recall, it's this work of all of those organs that burns calories. So that might mean that your digestion gets sluggish because your GI muscles are not contracting as strongly. You get fatigued and tired so that you don't accidentally or intentionally move too much

Starting point is 00:18:46 and burn more calories. Your sex drive shuts down so that you're not able to get erections. And for women, our body might shut down our menstrual cycle because our body knows there is no way in hell that we have the reserves to support a baby. And you might have a really hard time building muscle or maintaining bone because both muscle and bone turnover requires a ton of energy aka calories. And as we saw with the Biggest Loser contestants, the quote-unquote metabolic damage in very extreme cases can be very significant. Thankfully for most dieters who are like not on a weight loss show, we're talking about a 3 to 5% decline in metabolism, which is about a 50 to 150

Starting point is 00:19:35 fewer calories per day, mostly related to some loss in metabolic muscle mass. So if you are in a calorie deficit, the safest thing for your metabolism is to take it super slow by losing no more than 0.5 to 1% of body weight per week. The next important piece of this for everyone, but especially if you're in a calorie deficit, is to maintain or increase muscle mass with resistance training. The process of muscle turnover requires a lot of energy, aka it burns calories. And the muscle you build then burns more calories than fat. About 6 calories per pound of muscle versus 2 calories per pound of fat. Research suggests that resistance training increases metabolism way better than aerobic exercise, resulting in a 7% boost in resting metabolism.

Starting point is 00:20:31 So let's just say that Sally works really really hard in the gym and puts on 10 pounds of muscle. That's an increase in resting metabolic rate of around 60 calories. That alone is better than all of the hacks combined that you would have to do every single day that we discussed earlier. But there's actually a two for one deal going on with muscle mass.

Starting point is 00:20:54 Since your body is now more muscle dense, each movement you make costs more energy. So you might actually be burning an extra 110 to 150 calories per day. That is like 30 times what you are getting from that cold plunge or like burning your tongue off with chili peppers. Finally, my last tip here is to complement that resistance training by focusing on getting adequate protein.

Starting point is 00:21:22 Protein provides the necessary amino acids to help rebuild muscle for long-term metabolic benefits. So for that reason alone, it is very important for supporting a healthy metabolism. But as we've now established, metabolism is all about the cost of our organs doing their job. And the digestion and metabolizing of food costs calories as well. We call this the thermic effect of food or TEF for short and it accounts for 8 to 10 percent of our total caloric expenditure. Now

Starting point is 00:22:00 protein is actually the most expensive food macronutrient to digest, where about 20-30% of the calories from protein that you eat end up getting expended during digestion. And that is compared to just about 5-10% for carbs and 0-3% for fat. So when we look at best practices for weight loss, we see recommendations of like 1.6 to 2.2 grams of protein per kilogram of body weight per day, or around 20 to 35 grams of protein per meal. So eggs, Greek yogurt, cottage cheese, poultry, fish, tofu, beans, legumes and protein powder like the one I developed at New Theory are all amazing sources of protein that can help you to maintain or increase muscle mass and therefore contribute to a healthy metabolism long term. So, let me quickly summarize some main takeaways about metabolism. Number one, a healthy metabolism is about way more than just how easily you lose or

Starting point is 00:23:24 gain weight. It affects digestion, fertility, immunity, energy, and so much more. And as such, it's important for everyone to be considering, even if you're not trying to lose weight. Number two, there are a lot of quick fixes that claim to boost your metabolism, but these have largely insignificant effects on energy expenditure or how many calories you end up burning per day. Number three, even if they do increase daily calorie burn, they don't actually significantly increase fat loss. And finally, the best way to maintain or increase your resting metabolic rate over the long term

Starting point is 00:24:07 is to avoid extreme crash diets and focus on building and maintaining lean muscle mass through resistance training and adequate protein intake. And there you have it folks, metabolism 101. But this is really just scratching the surface here folks so please feel free to DM me or reach out if you have further questions you'd like answered on the show. Again, another huge thank you to Eric Williamson for his incredible expertise here. I highly recommend reaching out at the links in the show notes if you're looking for some one-on-one nutrition advice.

Starting point is 00:24:43 And as always, I would love if you would leave Bite Back a review and send it to your friends if you found looking for some one-on-one nutrition advice. And as always, I would love if you would leave, bite back a review and send it to your friends if you found this episode helpful. Signing off with Science and Sass, I'm Abbey Sharp, thanks for listening.

Bite Back with Abbey Sharp - Want to BOOST Your Metabolism? The Science on Metabolism Hacks for Weight Loss

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