A recently published article was brought to my attention by the BBC Science Focus website. Here they reported on a published academic article that evaluated a clinical trial of nutritional variation on ageing, titled: Short-Term Dietary Intervention Alters Physiological Profiles Relevant to Ageing [1]. This study worked on a dataset created initially by the clinical trial of another group, which was published under the title “The Nutrition for Healthy Living Study: A Randomised Clinical Trial Assessing the Effect of Protein Sources on Healthy Ageing” [2], published here.

This new study examined whether dietary manipulation of protein source and macronutrient composition affects the estimate of biological age in older adults, by looking at what the 2019 study found based on the nutrition they varied based on groups.

The Nutrition for Healthy Living study (the original clinical trial), was a 2 × 2 factorial dietary intervention trial involving 104 participants aged 65–75 years. Participants were randomized to one of four diets, in which the changes were in fat and carbohydrates and they kept the protein amount equal between meal plans:

1. Omnivorous/high-fat-low-carbohydrate
2. Omnivorous/low-fat-high-carbohydrate
3. Semi-vegetarian/high-fat-low-carbohydrates
4. Semi-vegetarian/low-fat-high-carbohydrate

What that study found is not part of this write up. What this article is about is how an academic paper, designing a really faulty setup, can create fake information spreading like wildfire across the globe!

The study was designed as a single-blinded, randomized clinical trial with a 2 × 2 factorial dietary design. Diets were either omnivorous or semi-vegetarian both with 14% of energy from protein and either high fat/low carb (37%–41% of energy from fat and 41%–43% from carbs) or the reverse (28%–29% fat; 53% carbohydrate). Each participant was thus randomly assigned to one of the four following diets: omnivorous high-fat-low-carbs, omnivorous high-carb-low-fat, semi-vegetarian high-fat-low-carbs or semi-vegetarian high-carb-low-fat. This is all great. However, the definition of what low carbs means is wrong. This study never ever evaluated any low carbohydrate diet. What they had was a slightly lower carbohydrate than the high carbohydrate. Here are the carbohydrate values for the 4 groups, see if you can tell which is what? The number is in grams of carbs and in () is the percent of carbs in the total diet plan:

214gr(41%)  |  271gr(53%)  |  226gr(43%)  |  276gr(53%)

To start with: there is no low carbohydrate diet on earth that contains greater than 150 gr carbohydrates and for most people the standard low carbohydrate diet contains between 20 and 50 gr carbohydrates a day. So there was no diet plan on this study that met the low carbohydrate model at all.

Here is what the heart of the BBC article is on the academic article:

“The fewest changes were observed in the omnivorous high-fat group, whose diet most resembled the one they were following at the start of the trial. Balance, rather than restriction, is the key to a healthy diet. But all three other groups showed a reduction in their biological age at the end of the four weeks – none more so than the group that had an animal- and plant-based diet with higher carbohydrates and lower fat. Crucially, those carbohydrates were minimally processed – repeating the test with supermarket white bread and a bag of chips would not yield such a positive response.”

Other than the last part of the sentence that is completely taken out of thin air, let’s examine the rest of what the science writer concluded and see if they understood the paper at all.

What The Study Actually Compared

The NHL trial was fully described in Ribeiro et al. (2019). What the participants ate in this 2019 trial is found in Table 1 in the Ribeiro 2019 paper [2]. I took the liberty and removed unimportant details like individual amino acid types and amounts and changed kJ to kcal to show the most important elements that you can relate to.

Note how the carbohydrates are high across all diets. The “high fat low carbs” (HFLC) diet is nowhere near close to being HFLC!

The Institute of Medicine Food and Nutrition Board established an acceptable macronutrient distribution range for carbohydrates of 45% to 65% of total daily energy intake. 40% to 45% of energy from carbohydrates (which is what we see in the experiment) corresponds to approximately 200 to 225 g of carbohydrates daily—this is the standard composition of slightly lower than normal carbohydrate levels that is incorporated in the Standard American Diet (SAD).

The National Academy of Sciences also has the following published statement: “The lower limit of dietary carbohydrate compatible with life apparently is zero, provided that adequate amounts of protein and fat are consumed” (page 275) from their 2005 publication [3].

General Guidelines for Macros

The general understanding in the nutritional fields is the following: nonketogenic low-carbohydrate diets contain 50 to 150 g/d (less than 30% of total energy), and the ketogenic very low-carbohydrate diets include 20 to 50 g/d (less than 10% of total energy) of carbohydrates in the diet—see here.

So did this study really evaluate the benefits of low carbohydrate diet? Absolutely not!

And even more revealing is the table that shows what foods they were served:

Table 2. Number of serves of core food groups per study diet

And this table makes the terminology in Table 1 even more striking: the original researchers’ “omnivorous high-fat, low-carbohydrate” diet contained 6.3 servings of grains + 6.7 servings of vegetables + 1.6 servings of fruit per day! There is zero chance of ANYONE eating the low carbohydrate diet eating grains! Zero chance!

At the same time, the meals provided only 0.2 serving red meat, 0.2 serving poultry, 0.2 serving eggs, and 0.1 serving high-omega-3 seafood.

So where in the world is this a low carbohydrate diet? In a low carbohydrate diet, either the amount of protein or the amount of fat or both exceed the percent oof carbohydrates provided in the meal! Carbohydrate forms the smallest part of the meal and not the largest!

There is no such high fat low carbohydrate diet that includes grains, legumes, and this much fruit and vegetables!

So what exactly did these papers evaluate? Absolutely nothing.

It is one thing to publish a horribly misleading academic peer reviewed paper that will mislead the academic world with garbage outcome! It’s not good but really hard to prevent in our modern “publish or perish” environment. And at least the general public doesn’t know about it and are not affected by it.

But it is criminal to create a headline to also mislead the layman world!

How (and why) does a science publication https://www.sciencefocus.com/news/this-simple-diet-change-could-slow-your-biological-age-in-just-four-weeks  (BBC Science Focus) publish such garbage as a headline news??!! Shouldn’t their science writers know better?

The Science Focus article was written by Roland Hughesv on September 26, 2026 at 2:00 am. This should never have been published. Trashy science is easy to write.

1.           Andrews, C.J., et al., Short-Term Dietary Intervention Alters Physiological Profiles Relevant to Ageing. Aging Cell, 2026. 25(5): p. e70507.

2.           Ribeiro, R.V., et al., The nutrition for healthy living study: A randomised clinical trial assessing the effect of protein sources on healthy ageing. Nutrition and Healthy Aging, 2019. 5(1): p. 43–51.

3.           Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids 2005. National Academy of Sciences;, 2005. 2005(2005): p. 275.