Human health

Why will dietary guidelines in their current shape keep on failing us?

Despite decades of promoting dietary guidelines, optimal cardiometabolic health remains elusive for most Western adults. Meanwhile, rates of obesity, diabetes, autoimmune diseases, and mental health disorders are rising globally, increasingly impacting low- and middle-income countries. Critics argue that these guidelines—shaped by cultural biases—rely on insufficient or overstated evidence and may inadvertently cause harm. For example, one-size-fits-all recommendations can undermine the body’s innate ability to self-select foods, while disregarding a large variety of healthful practices outside conventional models. This approach stifles debate and marginalizes alternative perspectives. In the case of low-certainty evidence, dietary advice should embrace individualized care instead and refrain from enforcing top-down directives. Collaboration between health professionals and patients is crucial to account for personal preferences, cultural traditions, available resources, and unique nutritional needs. The push for ‘plant-based’ diets and unsubstantiated calls to limit meat consumption risk jeopardizing nutrient security for vulnerable populations, especially the young. Similarly, the growing reliance on ‘alternatives’ to animal-source foods is not inherently healthier and even may introduce health risks. A more effective approach would prioritize adequate nourishment, emphasizing protein- and (micro)nutrient-rich foods while reducing the intake of ultra-processed products.

This subsection addresses the following four elements:

The current health crisis
The problem with dietary guidelines
Too zealous adherence is not necessarily harmless
Ways forward?

The current health crisis

The world faces a severe malnutrition crisis. While obesity rates among adults have more than doubled since 1990 and quadrupled among children and adolescents, the problems of hunger and underweight remains a persistent issue in regions like South Asia and parts of Africa. Currently, over one billion people are obese—double the number suffering from underweight—and by 2035, more than half of the global population is projected to be overweight or obese. With a few exceptions, this rise in obesity is nearly universal. In the US, two-thirds of adults are overweight or obese, with projections showing one in two becoming obese and one in four severely obese by 2030. Alarmingly, only one on ten US adults still have optimal cardiometabolic health.

CLICK HERE for further reading

A global state of malnourishment

The world is severely malnourished. Both chronic diseases and nutritional deficiencies are ravaging public health worldwide [Nelson et al. 2018]. Globally, about 150 million children under the age of five are chronically undernourished (stunted), almost 50 million are acutely undernourished (wasted), and almost 40 million are overweight [FAO 2024]. More than half of preschool-aged children and more than two thirds of nonpregnant women of reproductive age are deficient in at least one essential micronutrient [Stevens et al. 2022].

The double burden of underweight and obesity has increased due to an increase in obesity combined with a persistent problem of underweight in south Asia and parts of Africa [NCD-RisC 2024]. Obesity rates among adults have more than doubled between 1990 and 2020, while those among children and adolescents have even quadrupled. One in every eight humans is now to categorized as obese (>1 billion people), which is twice the number of those suffering from underweight, and more than half of the world population will be either overweight or obese by 2035 [NCD-RisC 2024].

Region-specific trends

The increase in obesity is nearly universal, with the exception of a few countries like France and Germany and although incidence rates remain low in Japan, China, and India [Global Health Observatory/WHO]. In the US, two on three Americans are either overweight or obese [Fryar et al. 2020], while one on two is expected to become obese and one on four severely obese by 2030 [Ward et al. 2019]. Only 7 [O'Hearn et al. 2022] to 12% [Araújo et al. 2019] of the US adults are in a state of optimal cardiometabolic health. In Ireland, >80% of older adults are abdominally obese, >50% being at high cardiometabolic risk [FSA Ireland 2021].

The problem with dietary guidelines

Public health nutrition strategies, including dietary guidelines, have been criticized for their ineffectiveness, lack of evidence, and rigid, one-size-fits-all approach. The field of nutritional epidemiology of chronic disease has been accused of overstating evidence and producing implausible conclusions, leading some to suggest that current dietary guidelines are so flawed they should be disregarded entirely. Preventive public health nutrition is often described as aggressive, presumptuous, and overbearing, marginalizing diverse dietary practices and cultural perspectives while imposing recommendations shaped by cultural biases, moralizing beliefs, and vested interests. Conflicts of interest further erode trust in these guidelines, particularly in countries like the US and UK, where ties between policymakers and food corporations compromise credibility. Additionally, traditional and minority diets are frequently overlooked, with Western nutritional ideals displacing indigenous practices. Meanwhile, overstated claims about the benefits of certain foods, such as whole grains and seed oils, often lack sufficient evidence, whereas some of the restrictive recommendations, such as those targeting meat and sodium, may fail to produce meaningful health outcomes.

CLICK HERE for further reading

Dietary change is obviously needed but current strategies are inadequate. Below are some of the main problems plaguing the dietary guidelines.

Failed policy

The current dietary guidelines should be seen as a failed policy. Despite decades of implementation, they have not achieved their primary goal of improving public health. Instead, the rise in obesity and cardiometabolic illnesses has accelerated, often in parallel with the widespread adoption of these recommendations. This disconnect between intent and outcome raises serious questions about their effectiveness and underlying science. Some critics even suggest that dietary guidelines have not only failed to achieve their objectives but may have inadvertently worsened public health. Critics call for a complete reevaluation of the process, emphasizing transparency, diversity of opinion, and evidence-based decision-making to create more effective and adaptive nutrition policies.

Bias and conflicts of interest

While defenders of the guidelines emphasize their rigor and transparency, critics argue they are shaped by entrenched biases. By emphasizing low-fat, low-cholesterol, and high-fibre options, the guidelines paved the way for the production and consumption of highly processed foods rich in refined carbohydrates and with added fibres and seed oils to create a health halo. Some critics have even accused the food industry of shaping recommendations through research funding, sponsorships, and lobbying. Various governmental nutrition advisers are indeed known to be paid by some of the leading food multinationals, potentially distorting the validity of nutritional recommendations due to major conflicts of interest, as has been shown for the UK [Borland 2024]. The situation in the US seems at least equally problematic [Mialon et al. 2022], also due to the USDA's alliance with food corporations as ‘strategic partners' [Nutrition Coalition]. By emphasizing low-fat and low-cholesterol options, the dietary guidelines encouraged the production and consumption of highly processed foods rich in sugar and refined carbohydrates.

Low-certainty evidence and overstated claims

The way dietary advice has been constructed and practiced in the US since the 1980s has been criticized as 'untrustworthy', lacking sufficiently strong evidence and rigor [Guyatt 2019; Johnston 2019]. For instance, several methodological quality and reporting problems were present in systematic reviews informing the 2020–2025 Dietary Guidelines for Americans [Bodnaruc et al. 2025].

Critics claim the process relies too heavily on consensus-based science. The slow incorporation of new evidence and the exclusion of dissenting scientific voices have hindered meaningful reform. Critics argue that the guidelines prioritize maintaining consistency with past advice over adopting recommendations based on emerging, rigorous science. This resistance to change perpetuates outdated advice, preventing progress in addressing modern health challenges. As a result, nutritional epidemiology of chronic disease has commonly been used to formulate implausible conclusions and overstate the evidence [Cofield et al. 2010; Schoenfeld & Ioannidis 2013; Ioannidis 2018].

For a criticism of the scientific evidence underpinning advice for the restriction of animal source foods (and red meat in particular), see elsewhere on this website. Similarly, advice to restrict sodium intake beyond current average intake levels is poorly supported by the evidence, especially for normotensive people [Graudal et al. 2017; Graudal & Jürgens 2018; Mente et al. 2021; Ezekowitz et al. 2022]. Moreover, some commonly claimed protective effects on specific health outcomes are not to be taken for granted, as may be the case for calorie counting [Fernandes et al. 2019], 'Mediterranean' dieting [Rees et al. 2019], fruits and vegetables [Young et al. 2002; Møller et al. 2003; Crane et al. 2011; Kaiser at al. 2014; McEvoy et al. 2015; Duthie et al. 2018; Peluso et al. 2018; WCRF 2018, Key et al. 2020; Alami et al. 2022], whole-grains and fiber [Ho et al. 2012; Peery et al. 2012; Yang et al. 2012; Clark & Slavin 2013; Kelly et al. 2017; Guo et al. 2020; Marshall et al. 2020; Sadeghi et al. 2020], intake of antioxidants [Huggins & Simsolo 2021; Luo et al. 2021], or polyunsaturated fat [Ramsden et al. 2013; Hamley et al. 2017; Hanson et al. 2020]. These effects are either non-existent or likely too small to be a game changer in a context of Western diets and lifestyles.

Overly simplistic

The guidelines have been criticized for their one-size-fits-all approach, failing to account for individual variability in dietary needs and cultural differences. By focusing on generalized recommendations, they may alienate or mislead populations whose nutritional requirements do not align with the prescribed norms.

Every body is different in the way it reacts to a given diet, with respect to nutritional needs, metabolic responses, endocrine regulation, etc. Overruling this diversity with monolithic approaches to dietary formulation may undermine the body's ability to self-select foods. For instance, a person's glucose response to duplicate meals can be very variable, even under controlled conditions [Hengist et al. 2024]. Also, whether or not one can adapt successfully to a vegetarian diet depends on genetic differences, for instance related to genes encoding functions in lipid metabolism and brain function [Yaseen et al. 2023].

In the case of low-certainty evidence, guideline recommendations should be weak, conditional, and more pluralistic, based on the health-related values and preferences of the guideline users, a component of evidence-based practice that is regularly neglected.

Dietary guidelines are arrogant and exclusive

Since official health bodies - and the advice they promote - represent expert opinion, this readily results in appeal to authority, hinders the debate on what constitutes an 'optimal' diet [see elsewhere], and suppresses and marginalizes dissident opinion. Alternative perspectives, such as higher-fat or low-carbohydrate diets, are often excluded, creating a narrow framework of accepted thought. Dietary guidelines may have to be seen as a class-based construct that merely tells us what already healthy people (white, educated, middle-class professionals) believe a 'healthy diet' is [Hite 2018]. This can be patronizing, pushing Western nutrition theory upon cultural minorities [Best & Ward 2020; Katz-Rosene 2020], and thereby neglecting 'complexities of nourishment that are at the heart of kinship, social life, and caregiving' [Burnett et al. 2020]. The result is often a monolithic 'one-size-fits-all' reductionist approach to food and nutrition [Katz-Rosene 2020], excessively relying on an animal/plant divide [see elsewhere].

'Preventive' public health nutrition displays all three signs of arrogance, being (1) aggressively assertive (pursuing symptomless individuals in the general citizenry), (2) presumptuous (confident it does more good than harm), and (3) overbearing (attacking those who question the value of its recommendations) [cf. Sackett, 2002]. Taken together, dietary guidelines describe opinion but fail to provide meaningful information about true diet-chronic disease relationships. Some argue that it may as well be wiser to ignore them altogether [Marantz et al. 2008].This is not to be considered as anodyne; in a biopolitical context, public health interventions can have serious ethical repercussions on individual responsibility and freedom, cause iatrogenic harm, and affect societal well-being [Mayes & Thompson 2015].

This is, for instance, the case for the 'Nunavik food guide', whereby a Mediterranean-style pyramid, rebranded as an igloo-shaped model, is used to 'reflect current issues in nutrition and to meet the needs' of the local Inuit [NRBHSS 2020]. Meat, fish, and fat, that were once at the heart of historical arctic diets [see elsewhere], have been strongly de-emphasized to the benefit of previously irrelevant foods such as vegetables, exotic fruits, (breakfast) cereals, and milk. Similarly, the Australian 'Aboriginal and Torres Strait Islander Guide to Healthy Eating' is superficially framed as a traditional dietary model but is once more based on Western nutritional dogma and at odds with indigenous eating habits [NHMRC 2015].

Too zealous adherence is not necessarily harmless

Excessive adherence to (or overinterpretation of) certain nutritional guidelines may have unintended consequences, especially for vulnerable groups. It can lead to overly restrictive diets, particularly when combined with food allergies that require additional exclusionary measures. Given the persisting call for more 'plant-based' eating, disproportionate reliance on 'protein alternatives' may result in higher consumption of processing contaminants and anti-nutritional compounds, as well as a higher proportion of ultra-processed foods. In excess, some improperly prepared or treated plant-based foods could lead to higher intakes of harmful substances like cariogenic sugars, fructose, mycotoxins, heavy metals, pesticide residues, plant-derived toxins, phytoestrogens, allergens, oxidation products, and acrylamide. Additionally, diets that are very low in fat and high in fibre may cause increased flatulence and bowel discomfort. The health impact of plant-based diets largely depends on the specific food items chosen, and individual health status should also be considered. Finally, nutrient profiling systems designed to assess the healthiness of foods, and used for Front-of-Pack labelling and nutritional advice, such as NutriSCORE, may lead to further aggravation, for instance by exaggerating the risks of animal source foods and serving as an alibi for even more ultra-processing.

CLICK HERE for further reading

As a result of an excessive insistence on the restriction of animal source foods [see elsewhere], devout adoption of the 'plant-based' eating message may not be without consequences for vulnerable groups [see elsewhere]. It may, for instance, lead to overly restrictive diets, especially when co-occurring with food allergies that require their own exclusionary measures [Protudjer & Mikkelsen 2020]. Also, it is likely that the increase of 'protein alternatives' will result in higher ingestion of processing contaminants and anti-nutritional compounds [Banach et al. 2022] and a higher share of ultra-processed foods [Gehring et al. 2021]. Concern has been raised related to elevated intakes of some plants (or algae), and their derived products, without the proper culinary treatments, as for the cooking of red beans [Food Safety News 2021].

in some cases, this could lead to exaggerated intakes of cariogenic sugars [Humphrey et al. 2014; Weerasinghe 2021], fructose [Gugliucci 2017; Goncalves et al. 2019; Amani & Fatima 2020; Geidl-Flueck & Gerber 2023], cereal grains [Bressan & Kramer 2016; Menta et al. 2018]; mycotoxins [Arroyo-Manzanares et al. 2019; Eskola et al., 2020; De Colli et al. 2021; Mihalache et al. 2022, 2023, 2024], toxic chemicals and heavy metals [Kumar & Sharma 2021; Vogel et al. 2021; Snoj Tratnik et al. 2022; Rango Godebo et al. 2023], pesticide residues [Wykhuys et al. 2020; Buchenauer et al. 2023], plant-derived toxins and anti-nutritional factors [Ames 1990; Gee et al. 1996; Kassie et al. 1996; Patel et al. 2002; Truong et al. 2010; Baasanjav-Gerber et al. 2011; Latté et al. 2011; Gilani et al. 2012; Al Hasan et al. 2016; Bressan & Kramer 2016; Felker et al. 2016; Mithöfer & Maffei 2016; Bernardino & Parmar, 2017; Gong et al. 2017; Malakar et al. 2017; Kuang et al. 2023], phyto-oestrogens [Setchell et al. 1997; North et al. 2000; Allred et al. 2001; Tuohy 2003; Wagner et al. 2008; Siepmann et al. 2011; Marini et al. 2012; Westmark 2013; Upson et al. 2015, 2016a,b, 2019; Lee et al. 2019; Bredsdorff et al. 2020], allergens, even in cooked legumes [Dölle-Bierke et al. 2022; Abrams & Gerstner 2015], oils, omega-6 fatty acids, and their toxic conversion products [Pearce & Dayton 1971; Simopoulos 2002; Ghosh et al. 2006; Novak et al. 2008; Feldstein et al. 2010; Ramsden et al. 2010, 2013, 2016; Alvheim et al. 2012; DiNicolantonio 2014; Schlörmann et al., 2015; Kim et al. 2017; Mamounis et al. 2017; DiNicolantonio & O'Keefe 2018; Tsurutani et al. 2018; Saeed & Naz 2019; Liao et al. 2020; Yamashima et al. 2020; Grootveld et al. 2021; McGinnis & Ji 2021; Quin et al. 2021; Wang et al. 2022; Deol et al. 2023; Duan et al. 2023; Jurado-Fasoli et al. 2023; Macarena et al. 2023; Mercola & D'Adamo 2023; Murdolo et al. 2023; Yamashima et al. 2023; Newport & Dayrit 2024; Zhai et al. 2024], and acrylamide [Amrein et al. 2005; Schlörmann et al., 2015]. Also, when diets are excessively low in fat and enriched in fibre, more flatulence and other forms of bowel discomfort may be experienced [Barber et al. 2023].

Some of these concerns are more worrying than others, many of which being based on isolated studies, experimental models, or weak evidence. Causal interpretations are often not warranted and the data should be contextualized and subjected to rigorous risk assessment. Evidently, the harm or healthfulness of plant-based diets will largely depend on the type of food items chosen [Satija et al. 2016; Kim et al. 2020; Gallagher et al. 2021; Oncina-Cnovas et al. 2021; Gehring et al. 2021; Asfura-Carrasco et al. 2022; Elliott et al. 2023; Petermann-Rocha et al. 2023; Wang et al. 2023; Rauber et al. 2024; Shen et al. 2024]. Also, individual health status should not be overlooked. For patients with non-alcoholic fatty liver disease, for instance, high fruit consumption can exacerbate steatosis, dyslipidemia, and glycemic control [Alami et al. 2022], while there may be a case for fibre-free diets in subjects with colitis [Kuffa et al. 2023].

The above-mentioned reductionist view on what constitutes a healthy diet leads to nutritionism and the setting of agendas [Scrinis 2013; Leroy et al. 2022]. This is being promoted and amplified by food corporations that consistently benefit from a methodology that favours the fragmented analysis of single nutrients and foods. As such, it has 'diverted attention from the study of the ingredients, additives, and processing techniques used in the manufacture of ultra-processed foods', while it 'has also obscured the broader social, commercial, and ecological determinants of dietary health' [Scrinis 2020].

Nutritionism as an alibi for ultra-processing

Nutrient Profiling Systems (NPS) that are inspired on nutritional orthodoxy only seem to aggravate the situation, exaggerating the risks associated with animal source foods and underestimating the risks associated with ultra-processed foods [Ortenzi et al. 2022]. It comes as no surprise that such nutrient-centric dietary models and Front-of-Pack labels (e.g., NutriScore or Health Stars) are usually embraced by food corporations [e.g., Nestlé 2020]. On the Spanish market, for instance, 1/4 and 1/2 products within the favourable NutriScore categories A and B, respectively, are ultra-processed foods [Romero Ferreiro et al. 2021]. Such models require small sacrifices but meanwhile associate the harms of the foods they produce with high energy density and elevated concentrations of specific nutrients (sodium, sugar, saturated fat, etc.), which can be conveniently addressed through what is the core expertise of such corporations: ultra-processing. Products are then reformulated to somewhat reduce the levels of some of these nutrients (e.g., with synthetic sweeteners, salt replacers, texturizers, flavouring agents), or by adding ingredients with a healthy aureole (e.g., fibre or vitamins). This says little about true improvement of the healthiness of a food. The adverse consequences of ultra-processed foods are generally independent of dietary quality or patterns, which undermines the idea that reformulation would mitigate against negative health outcomes [Dicken & Batterham 2022].

For a dedicated analysis of ultra-processed foods, see elsewhere on this website.

Ways forward?

Future health policies should move beyond a narrow focus on nutrients or even foods, and consider dietary patterns as well as the broader social, commercial, and ecological determinants of health. Instead of monolithic top-down approaches, a reappraisal of culinary legacies could offer more constructive options that accommodate personal and cultural preferences. Foods associated with the recent 'Western diet,' particularly ultra-processed foods (UPFs), should be approached with caution. UPFs may serve as a primary target for preventing non-communicable diseases, including colorectal cancer. Their harmful effects may be attributed more to the act of ultra-processing itself rather than the nutritional content. Adequate essential nutrition, including sufficient protein and micronutrients, should also be a focal point of public health policies to address deficiencies that persist globally.

CLICK HERE for further reading

The challenges for future dietary guidelines will be to 1) address today’s priorities, 2) be simple enough (but not too much), 3) be more flexible, 4) be sufficiently evidence-based, and 5) be effective.

Future health policies should not only limit themselves to understanding 'the role of the various dietary dimensions that mediate health (i.e, nutrients, foods, and dietary patterns)' but also 'account for the role of social, commercial, and ecological determinants of health' [Scrinis 2020]. As an alternative to monolithic top-down approaches, proposing a narrow view on what may constitute a healthy diet [see elsewhere], a reappraisal of our various ancestral diets and culinary legacies may be considered as a more constructive way forward. This has the potential to provide a myriad of fallback options that allow for personal and cultural needs and preferences [Best & Ward 2020]. In contrast, foods that are typically associated with the historically recent 'Western diet' (dating back a mere 4-5 generations), warrant suspicion. This is the case for high intake of sugar [Avena et al. 2008; Yang et al. 2014], refined grains [Swaminathan et al. 2021], often as high-carb/high-fat concoctions with seed oils.

Efforts to correct public health will need to deal with those dietary factors that trigger a metabolic state of hyperinsulinemia, chronic inflammation, and abnormalities of the vascular endothelium. Based on strength of association and mechanistic insights, the latter responses may not only have to be considered as the most important markers for diseases of modernity, but also as potential causes of metabolic dysfunction [Kohrt et al. 1993; Bao et al. 1996; Wang et al. 2007; Rajendran et al. 2013; Chen et al. 2015; Tsoupras et al. 2018; Adeva-Andany et al. 2019; Noakes 2021; Global Cardiovascular Risk Consortium 2023; Mederos-Torres et al. 2024] and alteration of the homeostatic body weight 'set point', for instance via changes in brain dopamine [Darcey et al. 2023].

In that respect, it is not fully understood to which degree specific foods negatively affect metabolic health in a clear and causal manner. However, it is known that the consumption of ultra-processed foods generally leads to higher energy intake levels and weight gain compared to an unprocessed diet [Hall et al. 2019].

In parallel to the avoidance of nutrient-poor and hyperpalatable foods, the concept of adequate essential nutrition serves as a meaningful foundation of public health, as protein and micronutrient deficiencies are still of major concern globally, including both the West and low- and middle-income countries [Bailey et al. 2015; Keats et al., 2019]. Adequate protein, vitamins, and mineral intake levels represent the true nutritional challenges for mid-century [Medek et al. 2017; Nelson et al., 2018]. Public health policies should take this unambiguous data as their main mission, rather than overemphasizing findings derived from nutritional epidemiology of chronic disease, and all of the problems that come with that [see elsewhere].

Share this page on: