Habits and Hustle Podcast Episode 510:

Layne Norton, PhD: The Best Diet to Follow + Is Diet Coke Actually Bad For You
Host: Jen Cohen
Guest: Dr. Layne Norton, PhD
Original Air Date: December 12, 2025

Overview

In this episode of Habits and Hustle, host Jen Cohen sits down with acclaimed nutritionist and scientist Dr. Layne Norton to dissect two hot-button topics: What is truly the "best" diet for long-term health and weight loss, and whether diet sodas (like Diet Coke) are actually bad for you. Dr. Norton brings a practical, data-driven perspective, challenging diet dogma and media-fueled fears, and offers actionable, sustainable advice for listeners striving for healthier habits.

Key Discussion Points & Insights

1. Is There a “Best” Diet for Everyone?

• Key Research Findings ([01:54]–[03:23])

  • Dr. Norton cites two major systematic reviews: one examining four diets, another looking at fourteen, both finding no significant difference in long-term weight loss between different diets.
  • Adherence is the Real Key: The most significant predictor of success was how well individuals stuck to whatever diet they were following, regardless of the specific macronutrient breakdown.
    • Quote:

      “Whatever you can stick to, whatever you can sustain is going to be the best diet for you.”
      —Dr. Layne Norton [02:23]

  • People differ widely in what feels “sustainable”. What feels restrictive to some may feel easy to others.

• Personal Story: Flexible Dieting ([03:24]–[04:02])

  • Layne shares his own early struggles with “eating clean” and bingeing, discovering that allowing himself flexibility (tracking calories and macros, but eating foods he wanted) ended cycles of overeating.
    • Quote:

      “For me, if I know I can have it, it actually makes me want it less.”
      —Dr. Layne Norton [03:39]

• Coaching Others & Selection Bias ([04:03]–[05:48])

  • As a coach, Layne noticed that people succeeded best with the method they chose and believed in, not necessarily what was “objectively best.”
    • Quote:

      “Flexible dieting has worked the most. But that’s a selection bias because people come to me because they know I’m a flexible dieting guy.”
      —Dr. Layne Norton [04:25]

  • Customization and autonomy in dietary preference matter most; there’s no universal best approach.

• Practical Tools ([05:04]–[05:48])

  • Dr. Norton developed the Carbon Diet Coach app, which gives users choices (plant-based, keto, balanced, etc.) and allows adjustment, reinforcing sustainability over dogma.

2. Diet Wars, Belief, and Cognitive Dissonance

([05:48]–[07:31])

• Dr. Norton points out that people often cling to what has worked for them, becoming “tribal” about their diet and resistant to new evidence—a phenomenon known as cognitive dissonance.
  • Quote:

    “What they found is…both things were equally as effective as causing the person to become more entrenched in their beliefs. …It actually caused them to double down.”
    —Dr. Layne Norton [07:12]

• Changing beliefs is hard—even when faced with contradicting facts.

3. Artificial Sweeteners & Diet Sodas: What Does the Science Say?

Addressing the Stigma Around Diet Coke ([09:55]–[10:00])

• Jen Cohen raises the social stigma and panic over diet soda, noting, “If you hold a Diet Coke around these days, it’s like, you might as well just hold a machete…”

The Data on Diet Sodas ([10:01]–[10:57])

• Correlation ≠ Causation:

  • People often cite studies showing links between diet soda and obesity, but Dr. Norton clarifies these are correlations, not proof of causation.
    • Quote:

      “That’s like saying basketball is causing people to be tall.”
      —Dr. Layne Norton [10:00]

• Randomized Controlled Trials:

  • When diet sodas replace regular sodas, studies show significant weight loss. In a recent meta-analysis, people who drank diet soda lost more weight than those substituting with water, likely because water drinkers often compensated with calories elsewhere.

• Metabolic & Gut Health: ([10:58]–[13:08])

  • The bulk of fear around artificial sweeteners and gut health comes from limited human studies—most evidence is from petri dish or high-dose rodent studies.
  • Some changes in gut microbiota have been observed, but it’s unclear whether these are harmful, beneficial, or neutral.
    • Quote:

      “When it comes to gut health, [Diet Coke] is one of the last things I’m worried about.”
      —Dr. Norton referencing Suzanne Devcona [11:56]

  • Real-world health tradeoffs matter: the benefit of someone dropping significant weight by switching to diet soda is very likely to outweigh any theoretical or unknown gut microbiome effects.

The 'Naturalistic Fallacy' and Chemical Breakdown ([13:08]–[14:21])

• Many oppose artificial sweeteners due to the “naturalistic fallacy”—the idea that artificial automatically means dangerous. Dr. Norton breaks down what aspartame metabolizes into (amino acids and a tiny amount of methanol, less than found in tomato juice), and explains artificial sweeteners are used in minute quantities due to their intense sweetness.
  • Quote:

    “You get 20 times aspartic acid and phenylalanine in a steak than you do in a Diet Soda.”
    —Dr. Layne Norton [13:49]

  • Rodent studies cited are often at doses thousands of times greater than humans would ever consume.

Final Take on Diet Soda ([14:22]–End)

• Dr. Norton is clear:
  • He’s not suggesting people should drink diet sodas.
  • Quote:

    “If somebody wants me to say that it’s bad for you, I don’t think you can objectively say that.”
    —Dr. Layne Norton [14:22]

  • If swapping regular soda for diet soda helps with meaningful, sustained weight loss, it’s almost certainly a “net win” from a health perspective.

Notable Quotes & Moments

• “You have to follow some form of restriction, but you should choose the form of restriction that feels the least restrictive to you.”
  —Dr. Layne Norton [02:23]
• “For me, if I know I can have it, it makes me want it less.”
  —Dr. Layne Norton [03:39]
• “We get into these diet wars. Everybody wants to be the winner and have their diet be best. And I’m like, shouldn’t the goal be to just figure out what works for people?”
  —Dr. Layne Norton [05:46]
• “If I can get somebody to stop drinking regular soda and drink diet soda, and they lose 50 pounds… you’re going to have a hard time convincing me that person is not healthier now for having lost 50 pounds.”
  —Dr. Layne Norton [12:44]

Timestamps for Important Segments

• 01:54 — Dr. Norton introduces the adherence-over-diet debate and summarizes key studies.
• 03:24 — Personal story about the shift from “clean eating” to flexible dieting.
• 04:25 — Coaching discoveries and the importance of dietary self-selection.
• 05:48 — Discussion about diet wars, bias, and cognitive dissonance.
• 10:01 — Sweep away fear about diet sodas with the actual science.
• 11:56 — Diet Coke's low priority in gut health concerns, quoting a leading microbiome expert.
• 13:08 — Debunking aspartame fears via its chemical makeup.
• 14:22 — Summing up: Is Diet Coke bad for you?

Conclusion

This episode offers empowering, evidence-based advice emphasizing practicality and personalization over fad, fear, or rigidity. Dr. Layne Norton urges listeners to gravitate towards consistency and adherence, not diet tribalism, and he systematically disarms common health scares around diet sodas with up-to-date research and relatable analogies. If you want sustainable, sane nutritional guidance, this conversation is a must-listen.