The Perfect Diet For Men Over 40 (According To Science)

What if the diet you keep quitting was never actually the problem? The perfect diet for men over 40 according to science is not the one with the best name.

Stanford put 609 adults on either a healthy low fat or a healthy low carb diet for a full year and the averages came back almost identical, about 12 lbs lost in one group and 13 in the other. Inside those same groups, some people lost 66 lbs while others gained 22. The researchers tested genotype patterns and baseline insulin secretion to predict who would do better on which diet, and neither one worked.

So the real question is not low carb versus low fat. It’s which eating pattern still covers your protein, fiber and nutrients when travel, bad sleep and client dinners get in the way.

In this video, I break down what the Diet Fits trial actually proved, why plant based and animal based approaches each make one part of your day easy and one part harder, what repeated resets cost your lean muscle after 40, and the four questions that decide it for you.

In this video, I cover:

About Zac Armstrong & No Hype, Just Standards: Zac Armstrong is a former Marine, Naval Officer, and F-18 Pilot who coaches executives and high-performing leaders to optimize their biological systems, overcome burnout, and achieve peak physical and mental performance using precision data.

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Transcript

Auto-generated from the episode audio and lightly formatted. Each timestamp links to that moment in the video.

0:00 Stanford put 609 adults on either a healthy low-fat or a healthy low-carb diet for a year. The average results were almost identical, about 12 pounds lost in one group [music] and 13 in the other. But within both groups, some people lost around 66 pounds while others gained about 22. That leaves a more useful question for anyone over 40. Which approach covers your basics and still works when travel, work, sleep, and client dinners get messy? Hey, look, if you’re new here, I’m Zach Armstrong. I’m a retired Navy commander and Marine and F-18 pilot. And now I coach men over 40 on their health, training, and overall performance. I’m going to give you four questions that will help you narrow the choice without pretending one diet fits everybody. So, let’s start with what the study actually did because I don’t want to stretch the results. The diet fits trial assigned 609 adults with overweight or obesity to a healthy low-fat or a healthy low-carbohydrate diet for 12 months. Both groups had real support and both were encouraged to improve food quality instead of the only chasing a macro number. At the end, the low-fat group had lost an average of 5.3

1:01 Kg, which is about 12 pounds. The low-carb group lost about 6 kg, which is about 13 pounds. That difference isn’t a very big statistical difference. The researcher also tested whether certain genotype patterns or baseline insulin secretion could predict which diet worked better. Neither did. Now, that doesn’t mean every diet is the same. This was a weight loss trial. It wasn’t a lean mass gain, and neither group was doing keto or carnivore. The study also didn’t prove that the adherence explained every individual result. What it does tell us is that the two supported approaches did produce one universal winner and that the two proposed ways of matching people to a diet didn’t fit one, either. From there, I just use a practical filter. The diet still has to help you manage how you eat, give enough protein to you, and have the nutrients that is needed for you to fit the lifestyle that you’re going to run each day. And each pattern makes a different part of that easier. Look at what each pattern ask of you. If you eat mostly whole food, plant-based, fiber, vegetables, and variety can be

2:02 Fairly easy. Protein is still completely possible, but getting enough at each meal takes more planning. You need to build around tofu, tempeh, soy foods, beans, and other concentrated sources. And if food alone makes one meal difficult, protein powder can help fill that gap. Check the serving on each label. That’s a useful way to start. It doesn’t need to replace the meals. With a strongly animal-based approach, protein in each meal becomes much easier. You have to pay more attention to fiber and plant food variety because those can drop out quickly. A short eating window can make the day simpler and can help some people manage the intake. It also means fewer meals in which to spread the protein. If your main goal is building or protecting lean mass and you struggle to eat enough protein in two large meals, that matters. So, when you look at any pattern, ask what makes it easy and what you will have to plan around. That is much more useful than arguing over the name. There’s another reason I care about this after 40. If you spend another year jumping on and off something and you can’t sustain, you’ve just lost another year in which your training, protein, and recovery could

3:02 Have been protecting that lean muscle mass. I’m not putting an exact rate on that. I just want you to understand that repeated resets carry more cost as you get older. And then there’s the calendar. And for most men, that’s the part that they undercount. Account for the week you actually have. You may have client dinners, travel, a marriage, kids, medication, and a schedule that you don’t fully control. A rigid plan can feel easy on a Sunday and fall apart once the week starts moving. So, decide before the difficult moment. If you have a client dinner, know roughly what you’re going to be ordering and whether you’re drinking before you get there. That takes a few seconds at home and saves you from solving the whole diet while everybody else is at the table waiting. And if the dinner goes differently than you planned, make the next meal normal. One meal has a limited effect across the month. Several days of writing the week off is a different thing. Here’s how it shows up for me. When I have a bad week, food usually isn’t where it starts. I still have work too long. Uh sleep goes, and then eating gets sloppy after that. By the third day, I’m short with people, and I’m not even doing better work. If I only look at a plate, I’ve missed where the week

4:03 Actually went wrong. Your health context matters, too. Blood pressures, lipids, glucose, medication, and history of disordered eating can change when tradeoffs are reasonable. If one of those applies, make the choice with an appropriate clinician instead of using this video as personal medical advice. There are two nutrient issues I would still keep in mind, as well. Some older adults, especially those with atrophic gastritis, absorb vitamin B12 naturally present in foods less efficiently. And a fully vegan diet removes the natural food sources of B12. So, if that’s how you eat, build a deliberate B12 plan with a qualified professional rather than assuming it will take care of itself, because it will not. Iron can be a problem in the other direction. Inherited conditions, such as hemochromatosis, can cause it to build up. So, don’t take iron because you’re tired and hope that the label explains it. Get the cause assessed properly. I’m not going to tell you your metabolism falls off a cliff at 40. Changes in lean mass, daily movement, sleep, food intake, and routine can all affect what you see on the scale. Those are the

5:04 Things I would check first. Now, let’s make the decision practical. There are four questions, and I would answer them in this order. Question one, what does your worst week look like? Think about the week with the flight, the late nights, client dinner, or family events. What actually happens? How often does it week show up? If it happens eight times a year, it has to be part of your plan. Write down where the eating normally breaks. Maybe it’s the airport. Maybe it’s the evening meal. Maybe after everything in the day has happened and you sleep badly. You’re looking for an approach that you can still follow reasonably well during that week. I would rather see you run a good plan all year than a perfect plan when the calendar is quiet. Question number two, which meal is currently your worst one? For most men, it’s breakfast. They have coffee, toast, cereal, or some small serving of eggs, and then a dinner has to carry most of that day’s protein. For you, it may be an airport lunch, the meal after a late work day, or the dinner where every choice gets made at the table. Whatever you choose should make that meal easier to handle. If it makes your weakest meal harder every single day, pay attention to that before you commit to it. And start with that

6:05 One meal. You don’t need to rebuild the whole week tomorrow. Question number three, what have you already quit and how long did it last? Look at what you’ve tried and when it broke. If you stop at roughly the same point every time, that gives you information. Three weeks may tell you the rule keeps running into your schedule. Several months may point to preparation, repetition, or social cost. That history doesn’t automatically mean you lack discipline. You may keep choosing a diet because you like the identity attached to it. Then find out if the actual routine doesn’t fit your life. I want you to use that history before you choose it again. Question number four, what are you actually trying to change? I want you to be specific about the result. Are you trying to protect lean mass, change body weight, improve how you feel in the afternoon, or address a lab result with your clinician? If lean mass is your goal, protein at each meal deserves more attention than you think. A short eating window or a small unplanned plant-based day can make it harder. So, you need to account for it. If fasting glucose has been rising, talk with your physician. You may end up paying more attention to carbohydrate load, what you eat, and liquid sugar.

7:05 You may also find that you don’t need a new named diet. A few specific changes inside the way you already eat may be enough to test. Goal tells you which trade-offs matter most for you. It doesn’t create one food list for everybody. So, write the four answers down: your worst week, the weakest meal, the plans you’ve already stopped and when, then the actual result you want. If those four answers point in different directions, don’t guess from another diet video. Inside Executive Health Edge, a licensed physician is going to review the labs with you. And I help turn that into a food plan for the week you actually live. If you want that help, the application is below. If you still can’t decide after that, choose a reasonable option that makes your worst meal easier and follow it long enough to see a multi-week trend. Use the results you named in the question number four and try not to change three other things at the same time. Whichever pattern you choose, the basic floor is going to stay the same. You still need protein at each meal, enough fiber and nutrients, and enough sleep to plan the work. Then your goal in your real week tell you what needs the most attention on top of that. Pick the pattern that survives your

8:05 Worst week and stop shopping. If the building and protecting muscle is the main reason you’re changing the way you eat, the next video is going to show you the five things I would check in order before changing that workout again. Watch how to build muscle as fast as humanly possible for men over 40 next.