The food system and climate change: are plant-based diets becoming unhealthy and less environmentally sustainable?

A plant-based diet, which can include small amounts of meat, is the foundation for healthy sustainable diets, which will have co-benefits for health, climate and the environment. Studies show that some of the barriers to making this dietary change and reducing meat consumption are perceptions that plant-based diets are inconvenient, it takes too much time and skills to prepare meals and ingredients are expensive. The food environment is changing and the industry is responding with the exponential increase in the market of highly processed, convenient and cheap plant-based foods. This overcomes some of the barriers, but there is concern about whether they are healthy and environmentally sustainable. Plant-based foods have a halo effect around health and the environment, but many being produced are ultra-processed foods that are high in energy, fat, sugar and salt and have a higher environmental impact than minimally processed plant-based foods. The trend towards eating more highly processed plant-based convenience foods is a concern with regard to both public health and the targets set to reduce greenhouse gas (GHG) emissions. The 'modern day' plant-based diet emerging is very different to a more traditional one comprising pulses, vegetables and wholegrain. Studies show that those who are younger and have been a vegetarian for a shorter duration are eating significantly more ultra-processed plant-based foods. While there is a place for convenient, desirable and affordable plant-based food to encourage dietary change, care should be taken that this does not subconsciously set a path which may ultimately be neither healthy nor sustainable.

Social, temporal and situational influences on meat consumption in the UK population.

The amount of meat consumed is having a negative impact on both health and the environment. This study investigated the probability of eating meat and the amount eaten at a meal within different social, temporal and situational contexts. Dietary intake data from 4-day diet diaries of adults (19 years and above) taken from the UK National Diet and Nutrition Survey (2008/9-2013/14) were used for the analysis. Individual eating occasions were identified and the effects of where the food was eaten, with whom, day of the week, age and gender on the probability of eating meat and amount of meat eaten were modelled using general linear mixed models. Each factor showed distinctive effects on the probability of eating meat and the amount consumed. The amount of meat eaten was greater when eating with family members compared to when alone or with other companions. Both the probability and amount of meat eaten in a single eating occasion were higher on Sundays compared to the rest of the week. Eating out (e.g. restaurants/cafes) increased the probability of consuming meat and the amount compared to other situations (e.g. home, work). When considering the factors influencing meat consumption, attention must be paid to the effects of social, temporal, and situational factors as they all work to shape consumption behaviour. This information should be used in the design of interventions and development of policies for the most effective way to reduce meat consumption.

Nutrition from a climate change perspective.

Climate change is threatening future global food and nutrition security. Limiting the increase in global temperature to 1·5 °C set out in The Paris Agreement (2015) while achieving nutrient security means overhauling the current food system to create one that can deliver healthy and sustainable diets. To attain this, it is critical to understand the implications for nutrition of actions to mitigate climate change as well as the impacts of climate change on food production and the nutrient composition of foods. It is widely recognised that livestock production has a much greater environmental burden than crop production, and therefore advice is to reduce meat consumption. This has triggered concern in some sectors about a lack of protein in diets, which hence is driving efforts to find protein replacements. However, in most high- and middle-income countries, protein intakes far exceed dietary requirements and it would even if all meat were removed from diets. Reduction in micronutrients should be given more attention when reducing meat. Simply eating less meat does not guarantee healthier or more sustainable diets. Climate change will also affect the type, amount and nutrient quality of food that can be produced. Studies have shown that increased temperature and elevated CO2 levels can reduce the nutrient density of some staple crops, which is of particular concern in low-income countries. Nutrition from a climate change perspective means considering the potential consequences of any climate action on food and nutrition security. In this paper, we discuss these issues from an interdisciplinary perspective.

Social deprivation is associated with poorer adherence to healthy eating dietary goals: analysis of household food purchases.

Background: The Scottish Dietary Goals (SDGs) were published to promote healthier diets. The higher cost of healthier diets may be a barrier to their adoption by households in deprived areas. The aim was to estimate dietary intakes relevant to the SGDs, derived from purchase data of food and drinks brought into the home by area of deprivation. Methods: A cross-sectional study of estimated intakes of food and nutrients, and on fruit and vegetables (F&V) specifically, from Kantar Worldpanel household food purchase data in Scotland from 2012 (n = 2586). Households were grouped by area based index of multiple deprivation. Results: Diets of households were further from achieving the SDGs as deprivation increased. Linear regression showed that estimated intakes of oil rich fish decreased, and red and processed meat increased with increasing deprivation (both P < 0.001), while estimated intakes of F&V decreased (P < 0.001) mainly because of lower amounts of fresh F&V (P < 0.001). Negative linear associations were observed between deprivation and the amount spent per person on F&V (P < 0.001), and the amount spent per 100 g of F&V (P < 0.001). Conclusions: This study provides further insights into the relationship between social deprivation and diet quality in Scotland, notably in amounts of fresh F&V purchased.

Dietary patterns of households in Scotland: Differences by level of deprivation and associations with dietary goals.

BACKGROUND: Foods tend to be consumed in combinations, and dietary pattern analysis and diet-quality scores are often more appropriate methods of assessing overall diet quality than is intakes of individual foods or nutrients. AIM: The aim of this study was to evaluate dietary patterns from the food and drink purchases of households in Scotland, and to identify any dietary patterns that were associated with closer adherence to the Revised Dietary Goals for Scotland (RDGS). METHODS: We carried out a cross-sectional study of estimated food and drink intakes using Kantar WorldPanel household purchase data in Scotland collected during 2012. The amounts of food and drink purchased were converted to estimated amounts available for consumption per person by adjusting for household waste, household size and composition ( n = 720). Dietary patterns were identified using principal components analysis. A Diet Quality Index (DQI), based on the RDGS, was calculated. RESULTS: The mean DQI score was low at 38 out of a possible maximum of 100, indicating that, on average, few of the dietary goals were being met. Six dietary patterns were identified, which explained 35% of the total variance in estimated food and drink intake. Three dietary patterns showed statistically significant associations with lower DQI scores (less healthy diets), and one with significantly higher DQI scores (healthier diets). CONCLUSIONS: Investigating dietary patterns to show which foods tend to be purchased together may assist in targeting dietary habits by focussing on key food groups, and in gaining the greatest improvement in diet quality from the most achievable change in diet.

Perceived barriers towards healthy eating and their association with fruit and vegetable consumption.

Background: Improving dietary intakes is a key public health target. Perceived barriers to healthy eating (PBHE) are an important component of the Health Belief Model which aims to understand why individuals do not adopt preventive health measures. This study investigates the relationship between PBHE and reported fruit and vegetable (F&V) consumption. Methods: Data from the Scottish Health Survey 2008-11 (n = 8319) for PBHE and self-reported F&V consumption were used in Probit regression models to test the association between meeting the 400 g per day F&V recommendation and PBHE. Results: Regression models show women who reported a lack of cooking skills were 10.4% less likely to meet the F&V recommendations (P = 0.001). Not liking the taste of healthy foods or finding them too boring (10.2%, P = 0.022), preparation time (5.6%, P = 0.020) or willpower (3.0%, P = 0.021) were also significant. For men, reporting not liking the taste of healthy foods or finding them too boring (6.8%, P = 0.02) was the only significant result. Price, a commonly reported PBHE, was not significantly associated with F&V consumption. Conclusions: Not all commonly reported perceived barriers to healthy eating are significantly associated with meeting the recommended F&V intake.

Using food intake records to estimate compliance with the Eatwell Plate dietary guidelines.

BACKGROUND: The UK Eatwell Plate is consumer based advice recommending the proportions of five food groups for a balanced diet: starchy foods, fruit and vegetables, dairy foods, nondairy sources of protein and foods and drinks high in fat or sugar. Many foods comprise ingredients from several food groups and consumers need to consider how these fit with the proportions of the Eatwell Plate. This involves disaggregating composite dishes into proportions of individual food components. The present study aimed to match the diets of adults in Scotland to the Eatwell Plate dietary recommendations and to describe the assumptions and methodological issues associated with estimating Eatwell Plate proportions from dietary records. METHODS: Foods from weighed intake records of 161 females and 151 males were assigned to a single Eatwell group based on the main ingredient for composite foods, and the overall Eatwell Plate proportions of each subject's diet were calculated. Food group proportions were then recalculated after disaggregating composite foods. RESULTS: The fruit and vegetables and starchy food groups consumed were significantly lower than recommended in the Eatwell Plate, whereas the proportions of the protein and foods high in fat or sugar were significantly higher. Failing to disaggregate composite foods gave an inaccurate estimate of the food group composition of the diet. CONCLUSIONS: Estimating Eatwell Plate proportions from dietary records is not straightforward, and is reliant on methodological assumptions. These need to be standardised and disseminated to ensure consistent analysis.

"It was an education in portion size". Experience of eating a healthy diet and barriers to long term dietary change.

The aim of the study was to explore the expectations and experience of actually eating a healthy diet and using this experience to identify barriers to healthy eating and sustainable dietary change. Fifty participants (19-63 yrs) were provided with a healthy diet (i.e. complied with dietary recommendations) for three consecutive days. Afterwards a semi-structured interview was carried out to explore expectations, experience and barriers to healthy eating. Using a thematic analysis approach eight dominant themes emerged from the interviews. Four related to expectations and experience of healthy eating; realisation of what are appropriate portion sizes, an expectation to feel hungry, surprise that healthy diets comprised normal food, the desire for sweet snacks (e.g. chocolate). This demonstrated there are some misconception about healthy eating and distorted views of portion size. Four more themes emerged relating to barriers to healthy eating; competing priorities, social, peer and time pressure, importance of value for money, a lack of desire to cook. Poor knowledge of healthy eating or a lack of cooking skills were the least common barrier, suggesting that future interventions and policy to improve dietary intakes need to focus on social, cultural and economic issues rather than on lack of knowledge or skills.

Effects of Snack Intake on Appetite, Affect and Attention.

To test the hypothesis that snacks eaten in the afternoon influence appetite, affect and performance on a simple attention task, an experiment was conducted using a dose-response design. Thirty male volunteers attended the laboratory on five occasions to consume a standard lunch and then to eat a snack three hours later varying in size and carbohydrate/fat content. The effects of consuming four snacks of increasing energy content (124, 274, 424 and 724 kcal) on ratings of hunger, fullness, appetite and mood as well as reaction time and accuracy in a perceptual discrimination task were investigated. Although appetite variables were responsive to the dose-response manipulation, mood and performance were only weakly influenced by snack intake. Lunch produced a greater impact on mood than snack consumption. The larger snacks decreased fatigue and only marginally improved reaction time. It is concluded that when level of deprivation, sensory, hedonic and expectancy effects were controlled, snack intake produced relatively subtle effects on mood and attention.

The sugar-fat relationship revisited: differences in consumption between men and women of varying BMI.

OBJECTIVE: To assess the relationship of dietary fat and sugar consumption in men and women with different body mass indices (BMI). To determine the actual food sources for sugar intake, comparing differences between men and women across BMI groups. The effect of excluding individuals with low energy intakes (that is, invalid data) on these relationships was also incorporated in the analysis. SUBJECTS: Subjects for this analysis were those individuals who participated in the 1986-1987 Dietary and Nutrition Survey of British Adults (DNSBA). METHOD: In the DNSBA, dietary intake was assessed using seven-day weighed food records, providing estimates of dietary fat and sugar intake. From the DNSBA database food records, sources of sugar intake were classified into five sugar containing food groups (high fat sweet products, fruits, dairy products, sugar products (excluding soft drinks) and sugar products (including soft drinks)). BMI was calculated from the measurement of height and body weight. RESULT: A positive relationship between BMI and dietary fat intake was found for men, both when fat was expressed as a percentage of energy and in absolute terms (g/d). This relationship was only replicated for women when intake was expressed in absolute terms. A negative relationship was found between sugar intake (as a percentage of energy) and BMI in men, but not women. Expressing sugar consumption in absolute terms did not produce a statistically significant relationship with BMI for either men or women. In women the only sugar source associated with BMI was high fat sweet products (for example, cakes, biscuits, chocolate), where higher intakes were related to higher BMIs. The reverse relationship was found for men. In men, BMI was also negatively related to the intake of sugar products (for example, table sugar, preserves, sugar confectionery), both when soft drinks were included and excluded. The inclusion of low energy reporters (LER) in the analysis altered the relationships between nutrients and BMI, particularly among women. The association between overall fat intake (g/d) and BMI was weakened, while the negative relationship with sugar intake was strengthened. In the case of women, the inclusion of LER completely reversed the relationship between consumption of high fat sweet foods (cakes, biscuits, chocolate) and BMI (due to the reduced reporting of these products by obese women). Fewer alterations in the relationships between BMI and the sources of sugar consumed were observed in men than in women when LER were included in the analysis. CONCLUSION: The relationships between dietary fat, sugar and BMI are different in men and women, and are dependent on the inclusion of LER, particularly in women. The results suggest that among women the consumption of high fat sweet products may be a factor in understanding obesity. Furthermore, the observation of high consumption of these foods among obese women is consistent with measured preferences for these high fat sweet foods. The altered representation of the data created by LER appears to distort the relationship between sugar, fat and the degree of obesity in men and women.

Fat as a risk factor for overconsumption: satiation, satiety, and patterns of eating.

Many people experience great difficulty in preventing energy intake from outstripping energy expenditure. Eating high-fat foods can facilitate the development of short-term positive energy balances by influencing satiation and satiety, the processes that control the size of eating episodes and the strength of postingestive appetite inhibition, respectively. An important feature of these processes is the relative potency of orosensory, postingestive (preabsorptive), and postabsorptive signals. Foods high in dietary fat have a weak effect on satiation, which leads to a form of passive overconsumption, and a disproportionately weak effect on satiety (joule-for-joule compared with protein and carbohydrate). This overconsumption (high-fat hyperphagia) is dependent upon both the high energy density and the potent sensory qualities (high palatability) of high-fat foods. A positive fat balance does not appear to generate a tendency for behavioral compensation, and there appears to be almost no autoregulatory link between fat oxidation and fat intake. The Leeds High Fat Study has found a higher frequency of obesity among high-fat than low-fat consumers, but the relationship between fat consumption and obesity is not a biologic imperative: analysis of the pathways between daily fat intakes and patterns of eating has revealed high-risk eating episodes. The physiologic responses to fat ingestion appear to be weak compared with the potent orosensory properties of high-fat foods, and such responses cannot prevent overconsumption. A first stage in a health program should be to prevent passive overconsumption.

High and low fat consumers, their macronutrient intake and body mass index: further analysis of the National Diet and Nutrition Survey of British Adults.

OBJECTIVES: To explore the different characteristics of high and low fat consumers, in particular their macronutrient intake and body mass index. DESIGN: Reanalysis of data from the Dietary and Nutritional Survey of British Adults. Comparisons were made between groups defined as high and low fat consumers on the basis of 7-day weighed food records considered to be valid for energy intake. Individuals were classified in two ways according to the percentage energy from fat (FAT%) and the absolute amount of fat consumed (FATg). The criteria for classification of the high FAT% being > 45% (high fat) and < or = 35% (low fat). For the FATg group the threshold for the high fat group was > 138 g/day (men) and > 102 g/day (women), and for the low fat group < 85 g/day (men) and < 70 g/day (women). SETTING: Dietary data was collected from private households in Great Britain between 1986 and 1987. SUBJECTS: From the total population of 2197, individuals who were slimming, ill or had an EI: BMR of < 1.2 were excluded in order to use data which was most likely to represent habitual energy intakes. From the remaining 1240 subjects, 10.8% of this sample (6.1% of the total population) were classified as low fat consumers (76 men and 58 women) and 15.4% high fat (8.7% of the total population, 93 men and 98 women). MAIN OUTCOME MEASURES: Macronutrient consumption and body mass index (BMI). RESULTS: 30% of the subjects changed fat group classification when the criteria of defining high and low fat groups altered from FAT% to FATg. Nutrient intakes differed according to definition of the groups. The high fat FATg group ate significantly more of all nutrients than the low fat FATg group. However, this was not seen for the FAT% analysis, with the high fat group eating more fat and less carbohydrate. The average BMI tended to be higher in the high fat than the low fat groups, particularly in the FATg analysis. However, the high fat group contained a wide range of BMIs. Further exploration of BMI in the high fat groups, showed that age (an 11-year difference) was the only variable to distinguish individuals in the top and bottom quartiles of BMI. CONCLUSIONS: High and low fat consumers differ according to a number of variables, and this is affected by how these groups are defined (FAT% or FATg). High fat consumers tend to have a higher BMI than low fat consumers, but not all high fat consumers are overweight or obese.

Control of human appetite: implications for the intake of dietary fat.

The human appetite system contains central and peripheral mechanisms that interact with environmental features, especially with the physical and nutrient composition of the food supply. Foods varying in nutrient composition exert different physiologic effects, some of which function as satiety signals. High-fat diets (low food quotient) lead to high levels of energy intake. This effect is termed passive overconsumption and overcomes fat-induced physiological satiety signals. High-fat foods exert a weak effect on satiation (intra-meal satiety), and fat has a weaker effect, joule for joule, on postingestive satiety than do other macronutrients. The frequency of obesity is greater among high-fat than low-fat consumers. However, the development of obesity on a high-fat diet is not a biological inevitability. The investigation of people who resist the weight-inducing properties of high-fat diets is a key research strategy. Understanding the appetite control system suggests behavioral, nutritional, and pharmacologic strategies for modifying dietary fat intake.

Mood modulation by food: an exploration of affect and cravings in 'chocolate addicts'.

To test the hypothesis that some foods are eaten to alter mood, the relationship between mood and intake of chocolate was investigated in 40 women. Twenty self-identified chocolate 'addicts' and 20 controls rated hunger, mood, intensity of craving and amount of chocolate eaten in a diary for seven consecutive days. The 'addicts' reported a significantly greater number of eating episodes and consumed a larger amount of chocolate than controls. 'Addicts' also rated depression, guilt and craving higher and feeling content and relaxed as lower before eating than controls. However, eating chocolate resulted in increased feelings of guilt in the 'addicts' and no significant changes in feeling depressed or relaxed. On indices of disordered eating and depression, 'addicts' scored significantly higher than controls; however, eating chocolate did not improve mood. Although chocolate is a food which provides pleasure, for those who consider intake of this food to be excessive, any pleasure experienced is short lived and accompanied by feelings of guilt.

Pleasure and excess: liking for and overconsumption of chocolate.

Responses to three different presentations of a highly liked food (chocolate) were measured in two groups of female subjects. One group of subjects identified themselves as overeaters of chocolate (overeaters), while the other group of subjects were of a similar age and body mass index, but ate this food in moderation (controls). The three conditions of presentation were (a) a fixed amount of milk chocolate; (b) ad lib access to milk chocolate; and (c) a self-selected amount of the individual's most preferred form of chocolate. The main findings were that variables associated with the excitation of appetite (hunger, desire to eat, prospective consumption) were higher in overeaters and variables associated with the inhibition of appetite (fullness, changes in pleasantness and pleasure of eating) were lower in overeaters relative to controls. It is suggested that investigations of individuals who eat certain foods to excess can inform our understanding of normative and aberrant eating behaviour.

"Chocolate addiction": a preliminary study of its description and its relationship to problem eating.

Definitions of chocolate addiction and its potential relationship to dieting and problem eating were investigated in 50 individuals who identified themselves as "chocoholics". Respondents were interviewed and completed a battery of questionnaires on food cravings, eating, weight, dieting and depression. On average this sample consumed about 12 (60-g) bars of chocolate per week and craved chocolate about six times per week. Cravings and amount consumed were not significantly related but amount consumed was significantly correlated with disinhibition (r = 0.3). Most (76%) respondents had definitions of chocolate addiction that centred on a lack of control around chocolate and regarded the "addictive" factor in chocolate as orosensory (i.e. taste, smell, texture). Unlike most others, dieters and secret eaters experienced negative affect following consumption of chocolate. Consumers who preferred to eat in secret reported a higher degree of aberrant eating. The extent to which the behaviour of "chocolate addicts" resembles that of eating disordered individuals and other addictions remains to be clarified.