The pattern of food intake differed across the age-ranges and according to the sex. Although both men and women showed high adherence to the “Sugar and fast food” pattern of food intake in the youngest age range, after this age, while women adhered more to a “Mediterranean-like” diet, men kept in “Sugar and fast food” diet, changing to greater adherence to the “Animal products” dietary pattern after the age of 65. The dietary patterns had significant associations with body composition and physical function, with more significant results in the middle-aged groups. Among middle-aged women, whether higher intake of “Animal products” was associated with higher lean mass, greater adherence to the “Sugar and fast food” diet was related to worse chair rise performance. Among middle-aged men, the more adherence to a “Mediterranean-like” diet, the lower body fat and lean mass. On the contrary, higher intake of a “Sugar and fast food” diet was associated with higher fat mass and poorer performance on gait speed, and higher intake “Animal products” was associated with lower grip strength. The associations between diet and physical function were independent of the body composition of the participants.
The preference for a diet rich in ultra-processed foods and lacking fruits and vegetables, as the “Sugar and fast food” dietary pattern, is often related to the low cost of these foods, lack of time, skills, and facilities to cook, their widespread presence, preferred taste, and emotional responses [24]. As the food components of this dietary pattern are energy-dense [25], it is not a surprise that greater intake has been associated with higher fat mass, as observed in the middle-aged men. These findings are in accordance with pooled data from cross-sectional studies that indicated a 39% higher risk of overweight/obesity with the highest consumption of ultra-processed foods [26]. In addition, in a crossover randomized controlled trial the ad libitum consumption for two weeks of an ultra-processed diet resulted in an energy intake 500 kcal higher than the alternate diet. As a result, participants had their body weight increased by ~ 1kg and body fat by ~ 0.5kg [27].
It is important to mention that among men over 65 years, greater adherence to the “Sugar and fast food” dietary pattern was significantly associated with reduced body fat, and tended to be inversely related to all anthropometric components, suggesting a risk of malnutrition [28]. Ultra-processed foods are poor in proteins, fibers, micronutrients, and bioactive compounds [25]. Thus, the “Sugar and fast food” dietary pattern may not provide enough essential nutrients for this stage of life [25]. In older adults, the consumption of ultra-processed foods was already reported to increase the risk of frailty [29] and grip strength decline [30]. In our study, higher adherence to the “Sugar and fast food” diet was associated with poorer performance on chair rise test in middle-aged women and in gait speed test in middle-aged men, independently of body composition.
The food components of the “Sugar and fast food” dietary pattern were already associated with some markers of biological aging. The intake of ultra-processed foods [31] and specifically sweetened carbonated beverages [32] have been associated with shorter telomeres. Furthermore, additives, added sugars, and trans fatty acids commonly presented in the ready-to-eat foods, could activate inflammatory patterns [33]. Longer time to complete the chair rise test is associated with shorter telomere length [34] and both chair raise and gait speed tests were already associated with inflammatory markers [35]. Thus, we can speculate that the pathways by which higher consumption of the “Sugar and fast food” diet could negatively impact physical performance involve telomere attrition and inflammation.
Higher intake of the “Animal products” diet was associated with higher lean mass in middle-aged women, but with a reduced grip strength in middle-aged men, which was unexpected. Meat is an important food source of high-quality protein and B vitamins essential to skeletal muscle; however, it also contains high amounts of saturated (SFA) and trans fatty acids (FA), especially when red-processed (which was the main type of meat in this dietary pattern). SFA and trans FA increase the circulating levels of pro-inflammatory markers [36]. In addition, we demonstrated a significant association between greater intake of “Animal products” and lower muscle quality in upper body by using the ratio of muscle strength to muscle mass in the arms as a proxy. Myosteatosis and the local inflammation as consequence of the SFA and trans fatty acids intake can lead to mitochondrial dysfunction, compromising the synthesis of ATP and increasing the levels of reactive oxygen species (ROS) [37]. This scenario favors the development of insulin resistance (IR) and impairs the fiber contractility, essential to muscle strength [38]. It has been demonstrated that the aging-associated immune-inflammatory changes occur first in men than in women, which may explain the negative association at an early age for men [39]. Interestingly, although not statically significant, greater adherence to this dietary pattern also tended to be associated with lower grip strength in women (non-significant association), but only when over 65 years.
The intake of processed meat (e.g. ham, bacon, sausages) have been associated with lower grip strength in the literature [40]. Processed meat has been additionally related to increased risk of frailty [41] and to impaired agility and lower-extremity physical function [42]. It is noteworthy that among the older men, the direction of the association between the “Animal products” dietary pattern and grip strength changed, a surprising result that needs further investigation. A potential hypothesis emerges from the concept of the “muscle clock”, in which the time of day when the intake of proteins occurs influences muscle response: the higher the intake at breakfast, the higher the grip strength compared to when protein is eaten primarily at dinner [43]. It has been observed that the percentage of protein intake at breakfast tends to be significantly higher in older adults compared to middle-aged counterparts [44].
On the contrary, the substitution of processed meat with fish, legumes, dairy, or nuts has been associated with a reduced risk of functional impairment [41, 42]. Since the foods contained in the “Mediterranean-like” diet are rich in antioxidants and nutrients with anti-inflammatory properties, this could mitigate the increased inflammatory environment associated with aging. However, in our population, the adherence to this diet was not associated with better physical function. We only observed significant association with body composition. In middle-aged men higher adherence to the “Mediterranean-like” dietary pattern was associated with lower body fat but also lower lean mass. This finding suggests that for men, perhaps the amount of protein achieved with the “Mediterranean-like” dietary pattern was not enough, requiring either increasing the protein sources presented in this diet (e.g., legumes and dairy) or including other foods rich in protein but low in fat, such as lean meat and eggs.
The limitations of this study include the cross-sectional design, which does not allow us to trace the trajectory of the changes in dietary pattern adherence, body composition, and physical performance and grip strength. Applying a retrospective food questionnaire has intrinsic bias related to memory; in addition, the use of a non-quantitative FFQ makes it unfeasible to estimate the nutritional intake of the participants. The results of this study should be interpreted with caution, as it is based on a population with higher economic and educational levels and with a good global lifestyle. Despite these limitations, this study provides concise information on the role of eating habits on body composition, physical performance, and muscle strength in a wide age range of men and women, corroborating in the understanding of the changes observed with aging.