AWEIL, South Sudan — One gauge of the famine looming in South Sudan is that people are simply collapsing from hunger.

As I was driving into this city, a woman was lying inert on the road. She was Nyanjok Garang, and she said she hadn’t eaten for three days. She had set out to look for work, maybe washing clothes, in hopes of keeping her two children alive. After a day of fruitless walking she had collapsed.

“My children are hungry,” she said. “I’m hungry. There’s not even a cent left to buy bread.” Her husband is a soldier in the government forces fighting in South Sudan’s civil war, but she doesn’t even know if he is still alive. So she left her children with a neighbor and set out in hopes of finding work — “and then I blacked out.”

A horrific famine enveloped what is now South Sudan in 1988, and there are some signs that this year could see a repeat. As in 1988, weather has led to poor harvests on top of civil war that has made it difficult to plant crops and move food around the country.

President Obama will be focusing on the South Sudan civil war in his trip starting Thursday night to Kenya and Ethiopia, both neighbors to South Sudan. The war is not only a military crisis but also a humanitarian catastrophe, which makes it all the more important to step up efforts to bring about peace.

You might think that what’s needed to end a famine is food. Actually, what’s essential above all is an international push of intensive diplomacy and targeted sanctions to reach a compromise peace deal and end the civil war. Yes, Obama has plenty on his plate already, but no other country has the leverage America does. And in peace, South Sudan can care for itself. But as long as the war continues, South Sudanese will face starvation — especially women and girls.

The gender dynamics of hunger are obvious: In Aweil, the hospital ward is full of skeletal women and girls, looking like concentration camp survivors. That’s because (as in many places around the world) when food is insufficient, families allocate it to men and boys, and women and girls disproportionately starve.

One 15-year-old girl in the hospital, Rebecca Athian, was so malnourished that her bones pushed through her skin and she had a measure of anemia (a hemoglobin level of 3) that in the West is pretty much unheard-of. Yet the hospital was now forced to discharge her to make way for new patients.

Rebecca has already lost two siblings in the last year, and although the causes of death were never fully determined, it’s a good guess that they were malnutrition-related. Her mother would like to marry Rebecca off, because it would then be her husband’s duty to feed her and keep her alive. But she says Rebecca has been raped, so men are unwilling to marry her.

The United Nations says 4.6 million people in South Sudan — more than one-third of the population — are “severely food insecure,” and the situation will deteriorate in the coming months because the next major harvest won’t come until October or November. Until then, there is nothing to eat.

“It is the first time we’ve seen so many cases like this,” said Dr. Dut Pioth, the acting director of the hospital. “It’s going to be like what we saw in 1988.”

Dr. Dut was 11 years old during that famine, and he remembers some relatives starving to death. His family fled to Khartoum, where he thrived in school and attended medical school. But he is frustrated because what patients often need now isn’t so much medical care, but rather food and peace.

To see starving children is particularly wrenching. They show no emotions: They do not cry or smile or frown, but simply gaze blankly, their bodies unwilling to waste a calorie on emotion when every iota of energy must go to keep major organs functioning.

It’s striking that this area of South Sudan is not directly affected by fighting; it’s calm here. But the hunger is still war-related, for the conflict is keeping food and supplies out. The road from the capital, Juba, has been blocked by fighting, and disputes with Sudan have closed the border to the north. So this area is cut off, prices are skyrocketing, jobs are disappearing, and ordinary workers can’t afford to buy food.

The only certainty is that it will get worse in the coming months, and the women and girls who die will be war casualties. “Those who are dying of gunshots,” Dr. Dut notes, “are fewer than those who are dying of hunger.”