Most replayed moment: The surprising science of weight loss | Alan Aragon & Professor Sarah Berry

28 Jul 2026 · 16 min · 7 chapters

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In short

Sustainable fat loss science, arguing that weight loss success depends on a net caloric deficit over time and on fixing “inputs” like sleep before diet tweaks; also explains why the scale can mislead and gives practical targets for weight-loss rate, protein, and training.

Guests

Alan Aragon is a nutrition researcher focused on evidence-based fat loss and protein targets. Professor Sarah Berry is a professor and sleep/research collaborator; she references sleep-extension (“slumber study”) findings.

Key claims

Sedentary living and a misunderstood need for a caloric deficit drive obesity; “magic foods” are confusion. Sleep is an “X factor”: <6 hours increases appetite/cravings and calories by ~150–300/day; adding ~2 hours reduces sugar intake and calories (~260–270/day). Scale weight is vague because muscle gain can offset fat loss; limit weekly loss to ~0.5–1% body weight (about 1 lb/week).

Notable examples

Sleep chamber studies (<6 hours) and a sleep-hygiene coaching trial (short sleepers increased to ~8.5 hours). Protein target ranges: ~1.2–1.6 g/kg (0.7 g/lb) general; ~1.6–2.2 g/kg (0.7–1.0+ g/lb) for fat loss/lean-mass preservation. Exercise “snacks” (desk band squats) and basic training patterns: push/pull/squat.

Written by AI. May contain mistakes. Listen to the episode to check what was said.

Chapters

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Understanding Obesity Causes

0:46 to 2:15

Exploration of factors leading to increased obesity rates.

“Alan, why are we becoming more overweight?”

Food Landscape Changes

2:16 to 3:25

Discussion on how modern food choices impact health and obesity.

“And they're almost hijacking our system.”

The Role of Sleep in Weight Loss

3:26 to 6:10

Examining how sleep affects appetite and weight loss success.

“I would start with, let's see your sleeping cycle.”

Realistic Weight Loss Goals

6:11 to 10:29

Insights on setting achievable weight loss expectations and factors to consider.

“So this deficit in calories is coming from the bad foods as well.”

The Importance of Protein

10:30 to 12:32

Discussing optimal protein intake for fat loss and muscle preservation.

“Now with that said, I don't think people should be discouraged if they're losing even half of that.”

Incorporating Exercise into Life

12:33 to 14:01

Strategies for making exercise enjoyable and part of daily routine.

“Exercise is similar to food in the sense that you have to find the type of exercise that you actually enjoy and even look forward to.”

Incorporating Exercise into a Busy Lifestyle

14:01 to 14:58

Learn how to integrate quick and effective exercise routines into your daily life.

“I think there's ways you can fit it into your lifestyle without it feeling daunting as well.”
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Transcript

Automatic transcript. May contain errors.

0:00Hello, and welcome to Zoe Recap, where each week we find the best bits from one of our podcast episodes to help you improve your health. Today we're talking about fat loss. For decades, we've been chasing the perfect weight loss diet. From Atkins to Carnivore, countless trends have promised remarkable results, yet failed the test of time. So how do we cut through the noise and find a formula that actually works? In this episode, I'm joined by nutrition researcher Alan Aragon and Professor Sarah Berry to unpack the science behind sustainable fat loss and explain why in some cases, the first step towards losing weight might actually involve gaining a little first.

0:46Alan, why are we becoming more overweight? It's a combination of several things. So the way that I see it, it is a gradual shift towards sedentary living. And this has been facilitated by labor-saving devices and even electronic and digital means to not even have to get up off the couch to prepare food. You just make a call and then wait for it to show up at the door and that's it. But in addition to that, there's a fundamental misunderstanding of how to maintain healthy body weight. And people simply don't know or are unaware that fundamentally, in order to lose weight, you have to impose a net caloric deficit over a period of time.

1:35And so when people are not aware of that, then they easily believe that there are magic foods that, for example, burn belly fat or magic foods that burn fat and then other foods that you should completely vilify or avoid. And that's where a lot of the confusion comes in. And in addition to that, I would say that in the present time, people have a greater tendency to use food to, I guess, medicate or entertain themselves just from general work, stress, interpersonal stress, anxiety. And so food ends up being kind of used as that sort of tool. I think that the combination of those things is at least some of the factors underlying the obesity phenomenon that has basically started in the early-ish 80s and continued on to today.

2:28To add to what Alan said, I do think as well as the fact that we're more sedentary, as well as we're all living such different lives and we have all of this food noise, our food landscape and the food choices that most people are making now are so, so different to 20, 30, 40, 50 years ago. And they're almost hijacking our system. You know, we have evolved to be able to handle excursions in blood sugar, to handle fat, to handle all sorts of things that are thrown against us. But we haven't evolved to handle the food landscape that's out there, that's evolving even more quickly than science can evolve.

3:04Maybe we can imagine a new client, Alan. So let's say they're in midlife. They want to lose, say, 10 pounds. Where do you start? And could you take us through the journey with them sort of step by step? Okay, so not everybody is ready to go on a program where they transform their body. Okay, let's say somebody thinks they're ready. I would start with, let's see your sleeping cycle. How much sleep are you getting? Do you feel it's enough? And what is your history with regard to that? Because sleep is the X factor for a lot of the success or failure in programs. Because when you don't get enough sleep, not only does it kind of affect the obvious stuff, meaning your energy to be physically active and certainly your energy to engage in any kind of progressive training program.

3:54But it also increases your appetite and your cravings, your hunger levels. It increases your cravings for calorie-dense, hyperpalatable foods. That's what sleep-deprived people mostly reach for almost instinctively. There's some very interesting research showing that subjects who are sleep-deprived consume, across studies, on average, about 200 to 300 calories more per day. while they're sleep deprived. There's studies where they actually take people into these kind of chambers and they monitor them for weeks and they actually sleep deprived them. They say, right, you're going to become a short sleeper, so less than six hours.

4:37And they see anywhere between 150, 300 calories per day increase in how many calories they're having just from depriving. I mean, it's a pretty cool study that these guys do. Yeah. And the interesting thing is it went the other way too. They took a group of habitual, less than six and a half hour sleepers and they put them through a coaching and training, sort of this education program on how to improve their sleep hygiene. And the goal was to add two hours of sleep a night. So they wanted to bring them up to, I believe, eight and a half hours or so. Seven hours of sleep appears to be this sort of threshold where, you know, below that it's, you know, the outcomes are somewhat adverse.

5:20So they trained these folks to bring their sleep average from less than six and a half hours up to eight and a half. And they ended up eating about 260-ish, 270-ish calories less per day, which is pretty dang significant in the scheme of things. especially when you consider that while they were sleep deprived, they probably had some sort of compromise in the amount of energy output that they had through either the exercise pathways or the non -exercise pathways, just lower spontaneous physical activity and less capacity for purposeful physical activity. So that's sort of the basis of everything.

6:07Get the sleep right. and also so by changing the sleep it changes the types of foods that you're having we did a study at king's called the slumber study which was one of those sleep extension studies where people who were short sleepers less than six hours of sleep were asked to increase by two hours exactly similar to the study you're saying and what we saw was that by people increasing their sleep they had no advice about what food to have at all all they were told was the here's good sleep hygiene we want you to increase your sleep and we happen as part of this to be measuring the kind of food you're having, they significantly reduce by quite a large amount the amount of sugar intake that they had.

6:43So this deficit in calories is coming from the bad foods as well. So we are in this sort of perfect storm where we're surrounded by all this terrible processed food and we've got these incredibly addictive phones, you know, with TikTok and Instagram, whatever, keeping us up late at night so we sleep less and then we need to eat more processed food. So there's a sort of, We are surrounded by this environment that is attacking us, aren't we? Oh, yeah. Bidirectional badness, basically. Yes. So you fixed my sleep. What happens next? Right, right. So fix the sleep. And then the other elements we're trying to simplify this is, okay, so you have a goal of fat loss.

7:26You have to make the individual understand that this is about fat loss. and the scale is just a very, very vague proxy of what's going on. And so the usefulness of what the bathroom scale is telling you will get progressively less. So it'll get more and more useless the more fit that you become and the closer you come to your goal. Why is that? Because some people can actually gain lean mass or muscle mass while they're losing fat mass. And so they're losing inches, their body fat percent is coming down, but the scale won't necessarily register that. And so people have to understand it's not 100 % about the scale telling you what's going on.

8:12I'll give you an example. So if you were to take somebody through who is completely untrained, they're fresh off the couch and their goal is to reduce their body fat in half. In that process, they may gain, depending on the time period, let's say it's a six-month period, they may gain up to six, probably more pounds of muscle mass during that period. And I would rather people look, when they engage a program, I would rather them look at the six to 12-month overview rather than the popular, okay, I want this in six weeks type of thing. And so if they understand that they're going to gain a certain amount of muscle mass just by virtue of engaging the right training program and getting their diet correct, then this is going to offset, who knows, six to 10 pounds of weight loss that they would have wanted.

9:12And in that case, that's where it becomes important for people to take note of how clothing is fitting, you know, take note of how that might reflect circumference measurements. If you have more fancy devices for guesstimating body fat percent like the InBody or Dexa, BodPod, any number of these devices, then that gives you a little bigger picture than what the scale is saying. But let's imagine that somebody just, you know, they don't want to wrap tape around themselves and they don't have necessarily access or they don't want to go over to get their body comp done at some facility, well then you would want to limit your weekly weight loss to, I'd say a maximum of 1 % of your total body weight per week at max.

10:03So if you lose more than that, then there's this tendency that you're sacrificing too much lean mass while you're losing fat mass. And so that would be the other sort of simple thing. We got the sleep, we got the rate of weight loss, you want to limit it to half a percent to a full percent. And really the one pound per week benchmark is fair. It's fair and it's realistic. Now with that said, I don't think people should be discouraged if they're losing even half of that. So if you're losing half a pound a week, two pounds a month, you know, heck that's still 24 or 25 pounds in a year. And most people have spent the last 10, 20 years putting on that 25 pounds.

10:53And so people have to have these realistic expectations of weight loss. So I would say half a pound to a pound a week is a good rate of expectation. If you lose more than that, then that's a bonus. And then finally, from just a sort of a programming standpoint, okay, we got the sleep, we got the rate of weight loss, and we've got protein. Most of the focus that my colleagues and I have been on research-wise has been on protein. So I have certainly a biased interest in protein. So the amount of protein that people consume per day that is optimal has been a matter of debate without overcomplicating it.

11:34In the general public, 1.2 to 1.6 grams per kilogram of body weight is a fair and realistic protein target for the general population. But I think that that is just kind of a good starting point. I really think you start getting into optimal and helpful for fat loss and lean mass preservation once you get to the 1.6 grams per kilogram of body weight. And in imperial terms, That's 0.7 grams per pound. If you fall somewhere between 1.2 on the low end, I'd rather see people do 1.6 all the way up to 2.2 grams per kilogram of body weight. So about 0.7 to one whole gram per pound of body weight is really sort of the sweet spot for the goal of weight loss or fat loss.

12:35Exercise is similar to food in the sense that you have to find the type of exercise that you actually enjoy and even look forward to. That's the way to get compliance. So as we get older, we just lose our functional capability muscularly because we just sit around and barely move. and for people who have really no clue as to how to engage like any sort of resistance training program, then you can just think of three basic movements in any variation of the planes, push, pull, squat. Those three movements, if you can engage those through, you know, a progressive amount of volume over time and you become familiar with how to apply effort to various movements within a simple pull, push, and squat type of thing, then there are ways to do full body training sessions.

13:41There are ways to do split sessions where you might do upper body one day, the next day you do lower body, and then you repeat that cycle again through the week. And then you have other splits yet where you're doing some variation of either the three times full body or the upper lower split, plus some specialization on a lagging body part. So that's some of the basics of it. I think there's ways you can fit it into your lifestyle without it feeling daunting as well. I'm someone that's never liked exercise. I've never been to a gym. I play a bit of tennis, But other than that, the thought of doing any kind of exercise class fills me with horror.

14:25So I'm just not going to do it. So I've started doing what I call exercise snacks because I am sitting at my desk all day. I am now 48. I do need to be thinking of not how I look, but my muscles, the fact that I know I'm at that age, they're all going downhill. And so I have by my desk one of those exercise bands. So I do what Alan says every now and then. You might see me on calls going like this. And squats every time I boil a kettle. I do squats. I can get 20 squats in. I have about eight cups of tea a day. That's 80 squats without even thinking about it. As you can imagine, hosting this podcast, running Zoe, juggling family life, it all keeps me pretty busy.

15:05So I try as best I can to stay energized and show up well in all those parts of my life by fueling my body with the right food, by exercising, and by adding a scoop of Daily 30 to my meals every day. If you haven't heard of Daily 30 yet, it's the gut supplement designed by our gut health scientists here at Zoe. It's made of over 30 high-quality hand-picked plants, including seaweed, fungi, and different types of fiber. Better yet, it contains ingredients that support gut health, digestion, and energy, which is ideal for packed calendars and busy lives. Simply add one scoop a day to any meal for an extra boost of fiber and plant diversity.

15:46And because it tastes delicious on just about anything and adds a satisfying crunch, it quite quickly slots into your life, becoming a daily healthy habit you'll always have time for. By the way, whenever we talk about Daily 30 as a good source of fiber, we're required to say that it contains four grams of total fat per serving. Obviously, that's all amazing healthy fats from plants. so order yours today at zoe.com daily 30 thanks for listening and see you next time

From the publisher

Today we’re talking about fat loss.

For decades, we’ve been chasing the perfect weight loss diet. From Atkins to carnivore, countless trends have promised remarkable results, yet fail the test of time.

So how do we cut through the noise and find a formula that actually works?

In this episode, I’m joined by nutrition researcher Alan Aragon and Professor Sarah Berry to unpack the science behind sustainable fat loss, and explain why, in some cases, the first step toward losing weight might actually involve gaining a little first.

🌱 Try our science-backed and tasty wholefood supplement Daily30

Get our brand-new app and Gut Health Test designed by world-leading gut health and nutrition scientists to build healthy eating habits 👉 Join ZOE

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📚Books by our ZOE Scientists

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Eating for Better Brain Health: Your brain-gut blueprint

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