Here's a possible explanation, but it's only a slightly-less-than-wild guess.

Men have seen rates of death from heart disease and heart attack fall quite significantly in the last 20 years. This is due in large part to wildly successful marketing campaigns about the signs of heart disease and especially heart attack. The reason only men have benefited from these campaigns is because the classic heart attack symptoms (chest pain, arm pain) are far more common in men than women. Women tend to have symptoms like severe heart burn, fatigue, and the like. Same disease, dimorphized symptoms. This led to a situation in the late 90s to mid 2000s (or thereabouts) where men saw dramatic declines in heart attack death, while women continued to rise in that ominous category. Some epidemiologists noticed this and they started making more ad campaigns targeted toward women. Since then, death rates among women have begun to stabilize for the most part and even come down some places.

The above is all true. Here's the speculative part. Obesity disproportionally affects poor people, and poor people are also the least likely to be educated about the signs of disease, not to mention the least likely to get treatment even if they're aware of disease. So put obese, uneducated, poor and female in the same category and you have a recipe for disaster. Possibly.