Examining Diet Trends: The Science Behind Today's Most Popular Diets
BLACK IRON RADIO EP. 345: Examining Diet Trends: The Science Behind Today's Most Popular Diets
Diet trends are not going anywhere, and neither is our need to talk about them.
Morgan, Krissy, and Jess break down the psychology behind why people keep falling for it, then get into the actual science behind keto, carnivore, paleo, intermittent fasting, and GLP-1 medications. Plus a cheat code for evaluating any diet, including the next trendy one that hasn't been invented yet.
The truth is most of these diets are just recycled versions of the same few ideas… repackaged, renamed, and sold to you with really convincing anecdotal evidence.
Every few years, a new diet takes over. The name changes, the marketing gets a refresh, and suddenly everyone you know is cutting out one specific thing and swearing by it. But the appeal is not new, and neither is the cycle.
In this episode of Black Iron Radio, Morgan, Krissy and Jess Gordon sat down to talk about why diet trends are so compelling, what they actually have in common, and how to evaluate whether something is worth your time or just another version of the same old playbook.
The Diet That Refuses to Die
Keto keeps coming up, and not just because it is popular right now. It has been popular, in one form or another, for decades. Atkins in the 80s and 90s. South Beach in the early 2000s. And now keto. The branding has changed, but the core rule has stayed exactly the same: cut carbs dramatically and the weight will follow.
The reason low-carb diets keep cycling back into fashion is that they do produce results, at least at first, and those results look striking. When you drop from 150-250 grams of carbs per day down to 50 or below, your body sheds water fast. For every gram of glycogen stored in your body, you hold three to four grams of water alongside it. So the initial scale drop is real and dramatic, but it is almost entirely water, not fat. The before-and-after photos look incredible, and that is exactly how the marketing works.
The other thing keto has going for it is that it simplifies decision-making. When most processed foods are off limits and your list of allowed foods is short, you eat less by default. You eliminate a lot of mindless snacking. If someone was previously eating a high-carb, low-protein diet with a lot of refined foods, switching to keto might actually represent a significant improvement in food quality. That is not the diet working magic. That is just a few core nutrition principles finally being applied.
Carnivore and the Even Harder Rules
Carnivore takes the same low-carb logic further, removing all plant-based foods entirely. No fruits, no vegetables, no grains, no beans. Just animal products: meat, fish, eggs, some dairy depending on who you ask. It is sometimes called zero carb.
From a pure nutrition standpoint, the concerns are real. Fiber disappears entirely. Vitamins and phytonutrients that only come from plants disappear with it. Saturated fat and cholesterol can climb significantly, and that matters for cardiovascular health over the long term. These are not minor trade-offs.
What drives people to it is the same thing that drives keto adoption: rigid rules feel relieving in the short term. You do not have to think about food. The list of what you can eat fits on an index card. And the initial results, again driven by water loss and calorie restriction through elimination, tend to feel validating.
Paleo: At Least There Are Vegetables
Paleo operates on the premise of eating the way our Paleolithic ancestors did, which in practice means eliminating processed foods, grains, legumes, and dairy. Unlike carnivore, paleo includes fruits and vegetables, which puts it in meaningfully better nutritional territory.
The irony, of course, is how quickly paleo morphed into a packaged food category of its own. Paleo muffins, paleo protein bars, paleo baked goods made in electric ovens. The spirit of the diet and the actual practice of it diverged pretty quickly.
But the core of it, eating whole foods, prioritizing protein, cutting out most ultra-processed products, reflects solid nutritional principles. The problem is not what it gets right. It is the rigidity, the labeling, and the long-term sustainability of maintaining those rules across a real, varied life.
Intermittent Fasting: The Window Problem
Intermittent fasting gets framed as a fat loss hack, but the mechanism is simpler than the marketing suggests. If a restricted eating window causes you to eat less overall, you will likely lose weight. But a restricted eating window does not guarantee you eat less. It is entirely possible to exceed your daily calorie needs in a six-hour window, and plenty of people do, especially when they arrive at that window hungry and eat quickly without registering fullness.
The deeper concern is what happens psychologically. For people with a history of disordered eating, hard rules around when you can eat can tip into obsession. During the fasting hours, food noise can get louder, not quieter. And when the window opens, you are not always responding to true hunger cues. You are responding to a clock, which tends to lead to faster eating and less awareness of satiety signals.
There is also a meaningful population for whom fasting simply does not work well: people who are pregnant, those sensitive to blood sugar fluctuations, people with demanding training schedules, and competitive athletes. For those folks, the cost of skipping meals or compressing intake is real performance and recovery impact, not just inconvenience.
GLP-1 Medications: Real Medicine, Real Trade-offs
GLP-1 medications like semaglutide and tirzepatide are a different category. These are not diets. They are medical interventions, and for the people who genuinely need them, they can be genuinely effective. They reduce appetite, slow gastric emptying, and quiet food noise in a way that lifestyle changes alone often cannot.
The issue is that the research is consistent on one point: when you stop taking the medication, the weight typically comes back. The drug works as long as you are on it, and staying on it long-term is not a simple or inexpensive commitment. Over time, some people find they need to cycle through different formulations as their bodies adapt. And for people without a clinical need for the medication, the side effects, including nausea, food aversions, significant muscle loss, and other quality of life impacts, can outweigh the results.
Using a GLP-1 to lose a modest amount of weight without addressing the underlying habits is a temporary solution. If and when someone comes off the medication, the same behaviors that contributed to the original weight gain are still there, waiting. The work of building sustainable habits has not been done.
What Effective Diets Actually Have in Common
Strip away the names, the rules, and the marketing, and most diets that produce results are doing a few of the same things. They reduce calorie intake, often just by limiting options. They tend to emphasize whole foods over processed ones. They put a meaningful focus on protein. And they provide structure that removes some of the daily decision fatigue around food.
None of that requires a restrictive label or a set of rules you have to follow forever. Those are the core principles we build around at Black Iron because they hold up long term, across real life, without demanding that you never eat bread at a wedding or stress about the airport food options on a work trip.
The relief that comes with rigid food rules is real in the short term. Having one simple guideline feels like it quiets the noise around eating. But after a month or two of restriction, the noise does not stay quiet. It comes back louder, because now you are also tracking what you are avoiding, feeling deprived, and negotiating with yourself constantly about what counts as compliant.
How to Evaluate Any Diet That Comes Your Way
A useful way to test any eating approach, whatever it is called, is to ask a few honest questions.
Does it require cutting out an entire food group? Elimination of a whole category is not necessary for health and is very hard to maintain across a lifetime of varied social situations, travel, and celebrations.
Can you actually do this in December? In July? During a busy stretch at work? If the honest answer is no, then it is not the right tool for you, regardless of what it promises.
Does it actually put you in a calorie deficit, or does it just make you feel disciplined? Weight loss comes from a calorie deficit. If the diet achieves that through restriction and elimination, it might produce short-term results, but the mechanism is not magic. There is no metabolic trick at play.
And is the appeal the results themselves, or is it the identity that comes with it? The community, the sense of doing something hard, the feeling of having rules to follow? Those are real psychological needs, and they are worth recognizing. But they are better served by building habits that actually stick than by white-knuckling through a protocol that was never going to last.
No one is here to judge what your aunt is eating or what worked for your friend last spring. But the goal is to help you recognize what is worth your energy and what is just a well-packaged version of the same old cycle. You deserve an approach that works in your actual life, not just in the six weeks before the before-and-after photos.
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If you enjoyed this conversation, check out more episodes of Black Iron Radio, where we cut through the noise and give you real, no-BS advice on feeling, performing, and looking your best. Each week we share practical nutrition, training, and wellness strategies and tips to help you succeed.
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