believed to be a major contributor to the rising rates of obesity. Portion size The portion size of many prepackage and restaurant foods has increased in both the United States and Denmark since the 1970s. Fast food servings, for example, are 2 to 5 times larger than they were in the 1980s. Evidence has shown that larger portions of energy-dense foods lead to greater energy intake and thus to greater rates of obesity. Meat consumption A 2010 study published in the American Journal of Clinical Nutrition closely tracked 373,803 people over a period of 8 years across 10 countries. At its conclusion, the study reported that meat consumption (processed meat, red meat, & poultry) is positively associated with weight gain and increased abdominal obesity in men and women. In response, the National Cattlemen's Beef Association countered that increased meat consumption may not be associated with fat gain. However, a subsequent response controlled for just abdominal fat across a sample of 91,214 people found that even when controlling for calories and subjects with cancer or smoking cessation, meat consumption is linked with obesity. Further population studies, reviews, and meta-analysis studies have corroborated the claim that greater meat consumption is linked to greater rates of obesity, especially in regards to red meat and processed meat. Sugar consumption Drinking more sugary beverages (including fruit juices, soft drinks, fruit drinks, sports drinks, energy and enhanced water drinks, sweetened iced tea, and lemonade) increases overall energy intake, and thus increases the risk of metabolic syndrome, obesity, and type 2 diabetes (see Obesity#Pathophysiology). Children who consume more added sugar in foods and beverages have a higher risk of becoming overweight. By itself, sugar is not a factor causing obesity and metabolic syndrome, but rather – when over-consumed – is a component of unhealthy dietary behavior. Adults who increase or decrease their free sugar intake increase or decrease their weight. Reviews indicate that governmental health policies should be implemented to discourage intake of sugar-sweetened beverages, and reduce the obesity in children and adults. Obesity has been rising in the 21st century. Other than adding excessive calories, the mechanisms by which high sugar consumption causes obesity are unclear because of limitations in clinical research involving uncontrolled factors, such as overall diet, physical activity, and sedentary lifestyle. Ultraprocessed food consumption Numerous large studies have demonstrated that eating ultraprocessed food has a positive dose-dependent relationship with both abdominal obesity and